External hard disk

Hello,
I HAVE A 80 GB SEAGATE EXTERNAL HARD DISK. WHEN I CONNECT TO THE PC THIS HARD DRIVE IS NOT CONNECT PROPERLY AND NOT FORMAT (WINDOWS WAS UNABLE TO COMPLETE THE FORMAT) AND SOMETIMES WHEN THIS CONNECT BUT THE DATA WAS CORRUPTED OF XTERNAL HARD DRIVE .......


PLEASE HELP ! ! ! ! ! ! ! ! ! ! ! ! !! !