Q: itunes will no longer open on my computer

I tunes will no longer open on my computer.   I unloaded ITUNES and then LOADED it again and it still still will not open on my compuer....I click the ITUnes Icon...looks like it wants to load, then I get a window that says, do you want to allow this program to make changes to your computer'  I click yes, then the screen gets cartoonish...all icons get fuzzy..and Itunes still does not open.  I have removed Itunes again, to get my comptuer screen back to the normal.   What the **** is going on?   It's always opened up just fine.  Help??