Original Portraits Files?

I tried to add mods to the game for the first time with different portraits but it didn't work so I put the original portraits files back only that didn't work either. Instead of the character's portraits showing, I get their sprite images. I've must have mixed the files up so now I don't have the original portraits files. I looked on the internet and can't seem to find them. If someone could help, I would really appreciate it.