If the hard drive has not failed yet there are signs that it may be going down for the count. You can troubleshoot hard drive problems and in most cases fix them. There are certain conditions where the only thing you can do is invest in a new hard drive. You may have been lucky enough to have received an error message, warning you of the imminent demise of your hard disk drive and you can at least back up your data. You can find information on backing up your data here. Vanishing Files and Folders If you know for a fact that you have not relegated files to the Recycle Bin and you no one else has access to your system it may be that your precious missing files are now the inhabitants of a bad disk sector. This may or may not be a tragedy depending on whether or not you back up all your personal files.  Clicking Sound from the Hard Drive Hard drive problems like a clicking disk drive can indicate head crash (the head is the reader that skims a fraction of an inch above the platters), damage to the hard drive's platters and alignment issues from being dropped, jostled or a power surge. When the sound becomes a grinding noise this may indicate that the head is resting on the platter and destroying your data bit by bit. Think of a needle skimming across the surface of a  vinyl record. We're all old enough to remember that right? Right? Damn, I'm old! There is no repair for these kinds of hard drive problems. The most you can hope for, if you do not back up your files, is to save some of the information on your system before it fails completely. I've heard of two different ways to help alleviate this condition long enough to access the drive and remove data. I have to say that I have not tried either method so I cannot condone or dispel the notion of each. * Turn the hard drive upside down. This is supposed to be gravity at work causing the head and arm to "fall" away enough to be able to read data. * Removing the hard drive from the system and place it in a Ziploc bag in the freezer for at least an hour, and then restoring it to your computer. This is physics at work. The reader arm is supposed to contract with the cold, moving far enough away from the platters to be able to read the data. Like I said I cannot condone the practices I just mentioned. If you want to research such exercises I would only do so if you cannot retrieve data from the hard drive any other way. Computer Reboots in an Endless Cycle Somehow I don't think this has anything to do with Da Vinci's musings on perpetual motion. A computer may reboot again and again when the boot sector has become corrupted or hijacked by a virus. However, before going to drastic measures, try swapping in new ram first. One PC I had to fix displayed all kinds of errors including the looping reboot failure, in the end it was found to be a bad ram stick. Some errors that point to the hard disk are easy fixes and not hard drive problems at all. Blue Screen of Death If you get a lot of BSOD errors on startup it could mean that your operating system is defective. Bad sectors on your hard drive may contain system information but your computer may be unable to read them. You can find help with a Blue Screen of Death error here. Hard drive problems such as this can be repaired and might not be fatal to your computer. Hang ups and System Freezing Bad sectors on the hard drive may cause your system to freeze or hang when accessing an application or file. Your computer will not be able to access information for the file or application on will subsequently freeze. You can troubleshoot for this kind of error by running chkdsk. You can also use chkdsk to attempt to repair these bad sectors. If bad sectors cannot be repaired you should consider these kinds of hard drive problems as drastic. At this point you should back up all the files that you are able to and consider buying a new hard drive. "Drive Not Formatted" Error When a "drive not formatted" or drive not recognized" error occurs it usually points to a damaged hard drive partition, a deleted partition or a corrupt one. Various practices can delete or corrupt a partition, these include, hard reboots, power outages and viruses. You should try to repair the disk using chkdsk or the windows repair utility for these hard drive problems. Hard Drive Problems by PC Apprentice 2009 - 2017 “I think it’s a new feature.  Don’t tell anyone it was an accident.” – Larry Wall