Ok this is what happened I installed Avast and restarted my computer like it said to go and when i turned it on the desktop wouldnt load so i googled some stuff on it about running in safe mode and repairing it and when i tried to repair it got an error and said it needed to be updated so i tried to update and it failed so right after i uninstalled it and restarted my computer and now when i start my computer i get a black screen the only thing i can see is my mouse pointer and i tried running in safe mode and the same thing happens… please help. thanks
can u please do this:
run aswclear as here: www.avast.com/uninstall-utility
now go ahead and download and re-install avast!
my computer screen is black i cant control anything now
are u able to access safe mode??
Nope 
screen goes black in safe mode as well
With both situations at black screen, maybe you need to boot with Windows DVD and try to recover it (backup, restore to a previous point, overinstall…).