I have a computter that was built for me and I got a virus at some point and formated my harddrive then my sister was messing with the computer and taking it apart to check it out and now I believe that I have put it all together right and it does not work I turn the power on and the fans turn and the lights for the drives come on but the monitor does not come on and the tower beeps like every 6 sec and never boots up HELP ME