Well firstly, COPY ANY IMPORTANT DATA OFF THE DRIVE ONTO CD, DVD OR ANOTHER HARD DRIVE.
That way if the drive does go you have not lost all your data.
I have had a look round the interent and it does look as though the drive is on its way out.
But it could also be that the cable connecting it to the motherboard may have come loose, or be faulty.
Or it may be that the hard disk controller on the motherboard has become faulty.
But overall the signs are not good.
If the PC is fairly old the hard disk may have just worn out.
Not sure how good your are with computers, but there are some things you can try, like checking the cable is secure at both ends, or trying a new cable.
Also putting the hard disk in another PC to see if it works, or putting a new hard disk in the PC and installing Windows etc and see if that fixes the problem.
I think you are going to have to do some more problem determination.