os problems

[nick]

i has the win32 virus on my comp, and i took it off. but
along with it went some important files. now i basically
cannot run exe files b/c it cant find them. a message
appears that says it can't find
C://windows/such_an_such.... even if u actually click on
the original file. the only way i can run anything is by
clikcing on "run as" where it allows u to choose
whichever user u want to run the program from.
cant figure out anything to do. tried to restore it and
it didnt work.