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A failing hard drive needs to be replaced as soon as possible. Its that simple.
Hard drives are not repairable, unless you specialize in this type of repair, and there are some companies that DO specialize in this, but only so that the DATA can be recovered from a broken hard drive.
This can be expensive VERY quick.....up to $1,000.00 (one thousand US dollars)
Mostly because of the facilities than go into the companies operations. Like a CLEAN ROOM to be able to open and fix a hard drive.
My best recommendation to you, is that if Windows has detected an issue with your hard drive (really no matter what the issue is) you should replace it.
But first, do your best to Offload all your DATA from the hard drive.
Then you can go through the process of restoring your data onto your new hard drive.
It is not a task ta***** *****ghtly, as the hard drive contains your OS too. So you will HAVE to HAVE the Windows Install disc to REinstall windows. If your hard drive has a recovery partition, you may have to get the Install discs sent to you, as they would not have come with your computer if you have a recovery partition. But what good is a recovery partition on a hard drive that is failing.....its a catch-22.
Backup your Data
Get the Windows Install Discs (for Windows 8, from the company you purchased your computer from (for example: Dell, Toshiba, Acer, HP) you may have to request it)
Put in NEW hard drive.
Install Windows on New hard drive, and restore your data from the back up