Windows doesnt load

Hello,
okay my problem is, that everytime windows goes to load (uses the hard to load windows) it freezes at first spin of the harddrive so i think i might be missing my startup .exe file so i was wondering if the start up .exe file was called somtin like ntvs.(enter extension here) or if not any suggestions on how to fix this problem and get my computer to start again. my computer was working fine until i let my friend use it and he thought a random file that appeared on the desktop was a virus and deleted it, since then this has happened. and help that can be offered gets a thanks in advanced.