UNABLE TO RE-INSTALL ITUNES! 10 POINTS BEST ANSWER!!?

hai =3...so ive been having major problems with itunes again...basically i uninstalled itunes and now i cant re-install it because i get an error message that tells me the file already exists. i am given a file directory address but i cannot find this "file" ANYWHERE on my computer! I am given two options(because the file already exists) to either replace or rename the file.I have no idea what to do and i dont want to deal wth customer service. Has anyone had a problem like this at all?? PLEASE HELP!!