Ive been trying to play a tank that can protect the party and be always the target of enemies, but only focusing on that, and not caring about doing damage and relying in my party.

Have you ever wanted to play something like this? How did it go? Also, if you would recommend me a class/subclass/race to play this id ve grateful!

Cavalier fighter. Take the sentinel feat. 
If you’re not worried about damage, go sword and board. Some of the class abilities, and one of the sentinel abilities, need you to be within 5 feet, so a reach weapon can end up working against you. And again, not worried about damage, you’ll want the AC boost from a shield.

Also, sword and board, you can take the protection fighting style, but probably don’t want to since it will compete with class and feat for your reaction. Instead take defense fighting style.

You can use class abilities to force enemies to attack you, and other abilities to help allies if they don’t. Just make sure the rest of the party gives you first crack when the plate mail rolls around. 

Very hard to Taunt in 5E, there aren’t a lot of abilities that force the DM to target you instead of someone else. Very very high level cavaliers can hard lock enemies in place on the battlefield with endless opportunity attacks, but before that... control spells like Entangle or even Spirit Guardians can keep enemies where you want them, and Thorn Whip, Lightning Lure, or Eldritch Blast enhanced by invocations can move enemies into those zones. A Cleric or Druid or Warlock focusing on high AC and Constitution can make a rather effective Control Tank. 

Just remember that not caring about doing damage doesn't mean not doing damage. Without some kind of a threat mechanic to keep enemies focused on you, you'll need to do something to keep them engaged. Doing some damage (a la Xalthu's suggestion to sword and board) helps to do that since you are still a threat.

Abilities that punish enemies for attacking other creatures (like the Cavalier's Unwavering Mark) and abilities that encourage the enemy to attack you (like the Barbarian's Reckless Attacks and the Paladin's Compelled Duel) are also important.

Utilising the threat of an Opportunity Attack, and control options like that found on the Crusher, Slasher, Sentinel, and Shield Master feats along with options like Ensnaring Strike are also good ways to effectively tank creatures and keep their focus on you (by limiting their ability to get to your friends. 

Finally, mechanics that let you change an attack or redirect damage to you are effective as well, particularly if you can limit the damage that hits you or efficiently heal it.

Perhaps the most important aspect of tanking in D&D besides being able to hit a creature (which you'll notice most of the abilities mentioned above require to trigger) is to simply be in the way. This is especially effective in cramped spaces where you can block a door or something, but it is important just by forcing creatures to go around you if they want to get to your friends. 

To illustrate, I was tanking a dragon and had decided to move away from the party to redirect the dragon to limit the possibility of the party taking damage from the breath weapon. It was a commonly used tactic in WoW when I was playing, but it was only effective because of the threat mechanic. Even though I was playing a Zealot Barbarian who was dealing quite respectable damage (probably 1st or 2nd on most fights) the rogue, warlock, cleric, and NPC were doing enough damage that they were considered the bigger threat (or at least it seemed like it was close enough that I didn't question it in the moment). The dragon therefore turned from fighting me, presenting me with an Opportunity Attack (which I missed), and then unleashed the breath attack on the rest of the party. This attack wasn't able to get the warlock, the rogue saved and was able to just barely survive, but the Cleric and the NPC both failed and went down. If the Dragon hadn't flown out of the building to regroup, we probably would have had a TPK. The only reason that the cleric was able to be included in the blast was because I has moved, allowing the dragon to move into the space just behind where I was. If I would have stayed, the Cleric wouldn't have been included and I had enough HP to weather the full blast even if I would have failed with advantage due to Danger Sense. I don't recall if both the rogue and the NPC would have been targetable if I'd stayed, but it would have been better considered everything and the DM may have chosen different tactics for the Dragon regardless.

Which brings up the final and most important part about tanking in D&D: the DM controls the actions of the enemies and can decide to do something completely off the wall, negating most of what I just said. This is especially true if the DM gives the creatures different personalities, including a hatred for a particular race, class, or other distinguishing feature that makes them attack that person regardless of any other circumstances (I made one subordinate in a group of goblins be romantically involved with the leader and attack anyone that killed the leader without any concern for their own well being, while other goblins would try to flee if the leader died or if they were under a certain HP level).

Ancestral guardian +echo knight + sentinel is a glorious tanking build.

Here is some strategy for your build:

1) You can be a tank by punishing people for NOT attacking you.  Protection/Interception Fighting Styles, Sentinel Feat, and Sneak Attack are all valuable tank skills because of this.

2) Dodge.  For the sake of all that is Orcus, Dodge.  If the only attack you get is an Opp Attack and it’s powerful enough, you’ll already be an amazing tank.  Consider this: If you get 1 attack per round that will hit 50% of the time and the two enemies beside you get 1 attack per round that will hit 50% of the time… 

Attacking will net you 0.5 hits and you’ll take 1 hit.  A net loss of 0.5 hits. 
Dodging will net you 0 hits and you’ll take 0.5 hits.  A net loss of 0.5 hits.  HOWEVER, if the enemy runs, you break even, with a chance of 0.5 hits on both sides.

3) You want to be a big target?  Grab a buff spell that you can cast, but never fail concentration on.  Nothing worse for a DM than when the PC who casted Bless is impossible to kill.  One level dip to grab this as a Fighter and you’ll be the hottest target by default.  Add Warcaster to the mix if you can and it’ll take Dragon Breath before you stop.  (Make sure to include yourself in the cast - Bless and Advantage on top of proficiency in Con Saves is just what you need. 

Just some quick pointers! 

There are a number of abilities that give disadvantage to attacks made against targets other than yourself.  That's always handy for forcing enemies to focus on you.

One word I haven't heard is lance if mounted cavalier, lt only needs one hand.  It gives 10'  reach, and my dog mounted mouse-folk can still use it.

I Try and convince the DM to let him Roll Deception rather than stealth.  (look at me I'm by myself, Oh you didn't see them.)
Plate of gleaming, lance with banneret flying, everything to draw the eye away from the rest.