Windows Xp problem

HI all. I have windows Xp with SP2, I got infected by virus (I don’t remember name of virus), but after updating my anti virus i removed virus from my PC, now after that the RUN command got vanished from my windows XP (i also tried to check it through task bar properties and it isn’t also there) and i cant use Task manager by pressing Ctrl+Alt+Del also cant use REGEDIT and it pops an error “registry edit is disabled by your administrator”, though i am login with administrator.
How can i recover registry edit and RUN command?? any help, can somebody shows exact procedure to recover these??
regards