Disk drive may be failing or my disk won't boot

Many times before a hard drive goes completely bad there are tell tale signs. If you can recognize them, there is a good chance that the data on the drive can be saved. The window of time in which action will be useful is quite small. Other than trying to fix the problem do not use the failing computer disk as you can just make the problem worse.
What are the signs to look out for? While there are few surefire signs of impending disk failure there are some warning signals that give us the hint. Watch out for: disappearing files, very long wait while accessing files, files/folders whose contents appear to be strangely scrambled, reoccurring error messages while moving/copying/deleting/creating files, and strange but frequent crashes of your OS. If your computer will not boot saying that it cannot find the boot disk or other messages similar, the boot sector may be corrupt.
Another telltale sign is any loud, low, irregular, clicking, or grinding sound which is emitted from the drive. This is the worst problem as your data and the disk are almost gone.
What to do? Download on a friends computer and create a bootable CD from one of these manufactures: Seatools from Seagate, the Data Lifeguard tools from Western Digital or Drive Fitness Tool from Hitachi.

• You must use a CD burning program (such as Nero Burning Rom or EZ-CD Creator) to burn a CD from the .ISO image.

Using the CD, boot the problem system. Make sure the BIOS is set to boot from the CD drive first, not the hard disk. Follow the manufactures instructions to test your disk. Do not let the program write all zeros to the disk or format the disk as you will loose all your data.
With luck, the program will repair any corrupt indexes.
Remove the CD and attempt to do a normal boot. If you can then boot into your desktop, immediately backup any data as the fix may be short lived.
If you don't have a CD drive, then you'll need to try using a bootable USB which is another topic.

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