I am not sure if I am not adding the addons to WoW folder properly or if they are actually faulty. Could you suggest me a trusted WotLK addon web? Also, could you suggest me the vital addons, because I don't remember what should I get as I just downloaded WoW after a break?
There's addon sections for each realm containing most of (if not all) addons for WotLK down below at the bottom of the forum page. They also contain instructions on how to put them.