'ERROR CODE:0141, MSG ERROR CODE: 2000-0141, HARD DRIVE:- NO DRIVE DETECTED'

IN my Dell Inspiron 1520 , whenever I start my laptop I get the message "Internal hard disk drive not found.
To resolve this issue, try to reseat the drive.
No bootable devices -- strike F1 to retry boot, F2 to set up utility.
Press F5 to run on board diagnostics."

 I ran onbiard diagnostics which showed following:
error code = 0141
msg error code = error code 2000- 0141
msg : no drive detected

I also opened the Hard Drive by removing hard drive screws to reseat the drive and put it back again as it was there intially.But when i started my Dell Inspiron 1520 , I get the same message -- "Internal Hard Disk Drive Not Found TO Resolve This Issue, Try TO Reseat The Drive" came.Please help me in this.