Hey guys, I am trying to make a weapon that has both a melee and a range attack with different values/damage types, I can't seem to find a way to give it both properties. Is there a way to give an item both melee and a ranged attack of different elements?

Thanks!

Unfortunately not, no.

Posta has answered the query but I thought I’d add a little background info - the only really effective combo weapon like that that had/has both missile and melee capability was/is the musket/rifle with a bayonet the musket (and latter multi shot rifle) give you the ranged attack while the bayonet gives you the melee attack. Originally muskets were so slow that the bayonet was simply plugged into the end of the musket to create a fairly heavy (and therefore unwieldy) short pike that at least gave musketeers a way to stand off cavalry charges with some chance of success. Latter the slip-over or clip on bayonet came into use along with faster firing rifles and true infantry melee with bayoneted rifles became common tactics. The rifle with a bayonet is a sufficiently effective weapon that militaries today still teach soldiers how to fight with it as part of basic training. 
 Your only real workaround here would be to take the musket and add a second weapon (bayonet or bayoneted musket) as a second weapon after talking with your DM. 
Useing crossbows or long bows would at best be treated as improvised weapons for melee. And yes there were a number of pistol+knife weapons created but they were never effective enough as either to be worth thinking about.

I would use a feat to represent the actions and then use the Manage Feats button to add it to characters with the weapon

Thanks for the added information, though I suppose that a bit of extra information describing the item here might help. I am currently working to port some of Elden Ring's weapons as homebrews into a campaign with the current task being the One-Eyed Shield. 

Essentially it is a heavy stone shield with a collapsible mortar in it, my idea to it was to make it two-handed, give it bludgeoning damage as a form of shield bashing, and then give it a projectile ability 5 charges with 1d4 charges replenished at dawn.

My current approach is probably going to be using the Maul as a base with +2 AC, and 5 charges of fireball that reduce movement speed of the caster to 0 when cast.

I don’t know the elden  ring or it’s weapons but the idea of a gun in a shield has been tried but wasn’t very successful and was single shot. A repeating mortar doing area damage might make since for giants but …. One semi - reasonable idea for getting that would be a regular bossed shield with a spiked boss that was enchanted to be a wand of fire or something similar.