Hi i am having difficulty getting my players to roleplay outside of combat which is outright going to effect the way the game plays later on. I would like ways to get them into the habit of roleplaying outside of combat without railroading them into it

Players tend to respond to the things they are offered by the DM. If you offer them combat, they will respond with turn based combat actions. Similarly, if you offer them roleplay, they will respond with roleplay. Unless they're murder hobos, in which case they will respond with turn based combat actions.

So, to engage them in roleplay - engage them! Make an encounter where they need to talk to a person to get a reward. An old captain, skin yellowed and a tankard in his only remaining hand, who if they talk to them well enough will offer them a treasure map, because he likes them - or they can intimidate him, or whatever. he has a treasure map, and is a conspicuous character, and they can go wherever they like with it.

I have spoonfed it myself - if the player says "I go into the tavern and order food, then go to bed", I will narrate them entering the tavern, and have the young waiter come over and ask what they would like, maybe being goggle-eyed at their weapons, and asking what adventures they've been on. Don't give them a "press X to skip the roleplay" option. If they want to be surly and silent, then perhaps they will make some enemies. Perhaps the kid takes offense and others stand up for him, saying "he's just a boy, why are you being mean to him!". Perhaps the roleplay needs to be forced down their throat, more of an ambush than an optional encounter. Maybe if they feel the mood turning against them, they will choose to try and improve things.

Make their popularity affect the world, as it would in reality!

Grant inspiration for creative roleplay. Even a player who's only interested in the mechanics of combat will at least pretend to roleplay if they get a tangible reward for it, and the more they do it the more normalized it becomes for them, the more it just becomes part of the gameplay and not just something they do because it lets them re-roll attacks. It also helps to give your players a subtle power boost early on while they're still learning their characters and how to play.

Use voices, even if you’re terrible at it. Actually, use voices especially if you’re terrible at it. As Dungeon Masters we have to show our players how to role play, sometimes and by being bolder than our inhibitions, unfettered by either a lack of talent or timidity, we can inspire them! 

So lead by example, I believe in you.

Quote from THEALMIGHTYDM1207 >>

…outside of combat…

That phrase there suggests to me an issue - that you are treating combat and non-combat as two different things. They aren't. Combat is just one way to resolve an encounter, with an encounter being some obstacle in the way of the characters.

You should make sure there are encounters where combat is a bad choice, or perhaps not an option at all. Maybe the characters need to obtain the key to the old mine, and the sherriff has it. Sure, they can attack the sherriff, but that will have bad consequences. Instead, they need to talk. Do they have something they can offer the sherriff in return for the key? Can they deceive the sherriff? Steal it from the office? Another idea?

For non-encounters (situations where the PCs are just interacting with the world) then make sure to throw in some conversation. The shopkeeper asks them where they are heading next. The barkeep asks about their travels. The smith asks where their weapons were made. Just little things that force the players to think about what the character would do in that situation (which, after all, is the definition of roleplaying). Sometimes these can lead to hooks (the shopkeeper says, "You're heading to Silverdale, can you take this letter?"), sometimes all they do is establish the personality of the characters.

Present choices that matter. Personally, I'm not really into just bantering at the inn - probably because I'm not really into that IRL either. That kind of roleplay is unlikely to have any consequence that affects the plot.

But if my character is faced with a hard choice, I will very happily examine the problem through my character's eyes and make a decision based on what I think they would do. Give them choices and then show the consequences of those choices. Don't be afraid to directly state the relationship between the two when those consequences happen. Roleplay is about doing what your character would do. When you see the results of that, it's like a reward in your brain and it makes you want to do it again.

And as G_W says above, a lot of those choices can happen during combat as well. Some might go so far as to say that only when your life is in danger do you show your true self. Shine light on the choices they make in combat - tie their decisions to their characters and present choices there too. If a goblin surrenders, do they trust it? Do they arrest it, execute it, let it go with a message, keep it as a pet? These are all roleplaying choices.

Is the problem lack of comfort or lack of will?

If its lack of comfort, practice will help. I've had several players who were nervous expressing themselves through roleplay at first. They wanted to do it, but weren't yet sure how and needed time to figure it out. I offered them plenty of opportunities for roleplay and, like Thoruk and DM_from_1975 said, modeled it for them through NPC voices and discussions, asking them questions in voice and letting them answer how they liked. Gradually, they got more comfortable with roleplay and were able to respond in their character's voice and express their character traits. Some more tips:

Have a positive gaming environment. If your players feel comfortable with you and the other players, they will be more likely to engage in roleplay. Make sure there is no negative responses like teasing for roleplay that doesn't work out or sounds awkward. 

Make sure you give opportunities for everyone. If some people dominate the roleplay more then others, have your NPCs ask the quiet players some casual questions. Don't push too much, though. No serious consequences for not roleplaying with these NPCs, just the benefit casual conversation. 

Don't try to force your players to talk. Give them chances, not requirement. Pressure will make them less likely to build comfort with roleplaying. Once they have gotten comfortable with it, then introduce important roleplay, where what you say really matters.

If its lack of will, show them just how fun roleplaying can be.

Enjoy it, illustrate how much fun it is to express your characters. Do voices, have different phrases and ways of talking for different NPCs. Encourage them to join you.

I hope this helps!

What is your definition of Roleplay? Is it playing the character with voices and emotions, having deep felt conversations lasting 15-20 mins with your NPC's about the mundane to try and get to the heart of things? 

Not all players want this, I currently am running a game for a group who are perfectly happy getting the pertinant information told to them in narriative form, they will tell me the questions the character is asking, they will explain how they are asking and I tell them the key details of the response. An hour spent "talking" to an NPC might be described and explained in about 5 mins or so, my current campaign is all based around an aboleth enslaving NPC's that the party already know and, even with this light touch roleplay, they have picked up that something odd is happening and NPC's are interacting with them differently. 

So before you try and improve roleplaying I would suggest talking to your players and asking them what they want, many many players are not ok "play acting" around a table or having those fake conversations, maybe have a read online about different roleplay approaches and tweak how you approach roleplay to make it easier for them to do in the 3rd person? 

Oh you can introduce them to roleplaying such as:

1st) The player meets an NPC who introduces himself but he's shady.  The players then talk about ambush and how to attack him, and the NPC interrupts them and says "Why are you planning on killing me?", let the players know everything they say in front of a NPC is heard.  Give them the opportunity to talk their way out of it.

2nd) Reward roleplaying with XP.  If a player has to make a tough decision that would go against what they'd like to do but the character would do, reward them with XP and inspiration.  Hell I reward players who roleplay with a hireling as an example of rewarding roleplaying.  Essentially acknowledge roleplaying and reward players as an incentive to encourage others to join.

3rd) Have a NPC come up and talk to some of the shyer characters on occasion and get their response.  A prod every now and then towards the right direction can elucidate a response.

4th) Have your humanoid NPC's, at least the boss of the lair open up dialogue and see what comes of it.  If the players always attack, it is what it is.  But perhaps if they had talked with the boss they would have gotten the words they needed to open that really cool chest that is invulnerable to all including Knock spell.  Maybe they'll resurrect the baddy for the passphrase, but now they'll have to find a way to get his confidence because he'll be scared to death of them and won't want to give away the only thing (pass phrase) that's keeping him alive.

5th) Describe the area, have standard behaviors for NPC's but then do slight changes over time.  Those slight changes should pique the players interest, if not, well let it play out.  Maybe a missing NPC has become a drug addict and when they see him again he'll try to steal from them or maybe now the NPC has joined a cult and is working against the players.  Did they notice it, did they talk to him before and after?

6th) Put up a quest board with quests and information and people to talk to.  Have the players come up to the NPC to get information.  Perhaps even have the guy only trust one of the members of the party, maybe he's racist or just doesn't like the smell of everyone else or just hates bards and paladins due to being sweet talked by them.  Don't allow the player to talk passive, when they do "yadda yadda yadda", have the NPC ask them to be more specific it went to fast for them.

So far, some solid advice handed out here. I might reinforce the idea that roleplay is not voice or character acting. Any time a player thinks from the eyes of their character or acts on some personality trait that is built into their character, they are roleplaying. It may not be what you consider roleplaying, but it counts for the player. When we as DMs think from the eyes of the villain or make world-shaking events on behalf of some omnipotent being, we are roleplaying. We are not required to make the sounds that accompany the action, only that we narrate the action well and use enough descriptors that it draws the players into the game world and keeps them there.

I agree with the principle of engaging players with choices and opportunities all of the time. Not just during combat. Combat is a method of conflict resolution, just like diplomacy is a method. One requires less talky-talky than the other, but they achieve an end to the conflict. 

I recently heard someone saying about their solution, which is "Give them a barrel".

When they are going to go somewhere, have someone arrive and ask them to take a barrel to someone at the other end. They tell them how important it is that this barrel arrive at the place.

If they ask why the barrel is important, or ask for a reward - congratulations, they are now roleplaying!

If they take the barrel, and one of the characters (cough-rogue-cough) decides that they want to look in the barrel, whilst another (EG paladin) says they shouldn't , they will discuss this - hopefully in character - then they're roleplaying!

Whatever goes in the barrel (make it as interesting or mundane as you like), it sounded like it really could up the roleplay of a group!