How do i get iTunes working again?

I am running windows 7 64-bit on my PC and recently I have had problems with iTunes.

When I click on the iTunes icon, it shows, that it is loading just for a split of a second and iTunes won't open. It only opens in safe mode.

A few days ago I installed TuneUp utilities and run maintenance on my PC, the program suggested some changes and I did them, cleaned my computer and after that iTunes just won't open. So I could really use some help as I have tried everything that was offered on support page.

Thank you in advance