Unplug your computer, open up the case and pop the battery on the moterboard out (this will reset the motherboard to defaults), plug the computer in and turn it on. If that fixed your problem, please turn off the computer and put the battery back in. If not, please tell us more about what the screen shows.
There is a chance your hard drive is not connected. Perhaps one of the cables came loose.
Remove the battery but make sure the BIOS jumper is in 1 and 2 position because 2 and 3 position will take the system directly to BIOS menu.