How can i install itunes if it doesn't let me because of bonjour?

I downloaded bonjour (something from itunes or apple) and it was fine at first but then later on my itunes started to fail and then it said "error". what the french toast! idk what happened but it stopped working and it wouldn't even let me open itunes. i deleted everything of itunes and i tried to uninstall it but it wouldn't let me because it said something about bonjour not being found or something like that...now i have no itunes on my laptop! this happened last year :( and i tried everything to try and uninstall it. i even when to the apple website for help and i did the directions it told me to delete itunes but it didn't work. then i downloaded some device thingy that forces a program to be uninstalled but that didn't work either! i already have no internet because of smart engine i think nd no itunes! all i have left is the sims :( i tried to install it again and it wouldn't let me, it was saying that i didn't uninstall the other itunes (i was trying to install the newer one). please help! oh and what is bonjour cuz idk wat it is...