when i was start the my laptop i got the this message with blue screen

Code:
set up did not find hard disk drives installed in in your computerbut i restart the several time the my lap top.its become ok. its happened 1 months ago.
but now a same message with same problem.i try to restart machine more than 20 times but its not working.
i went to BIOS and check my harddrive its showing.YES its showing. then i try to reinstlled the windows but again its telling no harddrive.
please help me to solve this problem.b'cos my uni assigments are there.