"rebooted it"....if you cannot see anything on-screen, how exactly did you 'reboot' your PC?? Was your OS operating before this occurred?? I.e. - did the monitor go dark while you were away?? Or, did you Power-On your PC this last time and then see only a dark screen?? Not even a small flashing cursor?? (The devil is in the exact specific details...it has been said.) With more info we may be able to assist.