I think I broke my computer...again

I decided to delete the two acounts to log into my computer because I never
use them and there wasn't any important information in them. When the login
window comes up, I just usually hit cancel anyway. So i deleted them and
restarted my computer and then it stated up and went to windows, then it
displayed message saying something about not being able to read the registry
or something. So I decided to to a system restore and put in the disk and
followed what it said to do to re-install windows. Half way through (i did
this twice, just in case) It would say something caused an error and if I hit
ignore nothing happend and when i hit close a black screen showed up and said
something about "couldn't read drive A" and then it said "Abort, retry,
fail?" and it didnt do anything so i re-booted and now evetytime i try to
open something an error message for this, or an error message for that shows
up. And the message that says "cant read system registry" or whatever is
still there. I don't know what to do. someone please tell me how to fix my
computer.