I'm a little concerned that you "knocked your computer off" at all, regardless of if it's an accident or not.
When you reinstalled it did you remove the old version first, or just try installing again? if the latter then try removing it first and then installing again.
I'd also now run a full check disk on your computer as if it's been dropped and is having problems the chances are you've damaged the hard drive. if you run a check disk and it reports a lot of errors I'd make sure you have a backup of everything important while you can and be prepared for your hard drive to die totally soon!
(and yes, please stop shouting)