try checking the cable that connect the system hard disk to the computer. also check if the hard disk is making a click sound, if it make click sound it mean its probably bad but if it doesnt it means it is good. then enter your bios setup.. it is usually indicated by a function key during the startup of the computer. check if it is reading from the hard disk ..if it is not try to put hard disk as the first boot order.. i think that should be the possible solution.. or u can give it to computer repairer..