Holla, I need some help with the mess I have created on my Mac.I deleted Mackeeper...now I have problems everywhere :/

So the story goes, I for some reason thought it'd be smart to delete mackeeper, I guess not. Since I have done this, I now get survey pop ups, slow slow navigation of my mac and some of my itunes files have entirely vanished.... I put Mackeeper in the trash and deleted it along with the few things in there... before this started happening... I now apparently have to pay to have Mackeeper again? I thought Mac was great in the no virus department or am I an undercover genius and figured out how to properly mess up my Mac to the point that virus's have taken over? I also noticed I had a file convertor where I was able to watch my avi files through has disappeare, entirely no trace of the program.. Is this something I may be able to do or is the shop best off having it?