If you are experiencing any signs or symptoms of potential hard drive failure or data loss or suspect that you may be having a problem with such then the first thing and most important to know is that time is critical.
You may experience data loss as a result of some virus or other software related problem or your hard drive may indeed be mechanically failing.
If your hard drive is mechanically failing and about to give up the ghost there isn't much can be done to save the drive itself. The name of the game at that point is to get off as much VITAL data as possible. Not all programs and data on your computer needs to be backed up only those things which are most important to you. So at this point its all about triage data saving. For example if you have pictures or music that you can not get again then you may want to attempt to back up your entire music folder and picture folder. Same thing with any word documents or anything you think you may not ever be able to obtain again THAT'S the kind of data you are looking for at this point.
How to back up your data quickly in a hard drive emergency...
If you are able to get on your computer and see your desktop then you want to insert a flash drive or some other external drive which you can quickly throw files onto. The idea is to KNOW where your vital data is located, go to it quickly and drag and drop it into the external drive! If you have a slave drive which you believe to be intact and not experiencing any problems. You may also throw back up data onto the hard drive of a network connected computer if that's still functioning.
First signs of mechanical hard drive failure...
When a drive starts to go bad it deteriorates very quickly with in minutes or hours or days if you are lucky.
The computer may start randomly freezing up. On start up the computer may require to run a disk scan. If it does let it run its scan. At the end of the scan pay close attention to how many bytes there are in known bad sectors. Ok ok ok =P let me explain a little bit about that. Your hard drive has like little pockets where it stores information those pockets are called sectors some times those pockets can go bad. In fact all hard drives have at least a small amount of bad sectors, that's normal lets say around 32kb (kilobytes). What you are looking for however is if the amount of data in those bad sectors is abnormally large lets say larger than 32kb. Now after the scan is done the computer will quickly list a bunch of stats and numbers before it resumes normal start up. What you have to do is look down where it talks about bad sectors and see the number of kilobytes or megabytes are located in those sectors.
If you couldn't see it in time before the computer started back up fully then you can click on start, my computer,right click on local disk(C) (its usually C it might be another letter) click on properties, then click on the "tools" tab at the top then hit the check now button on error checking select "scan for and attempt recovery of bad sectors" and "automatically fix the file system errors" then begin the scan.
Click on the image for an animation walk through of starting a scan
IMPORTANT NOTE while scanning you can run no other programs nor is it advised to open any folders or do anything really. Just make sure you shut down all your programs including Internet and e-mail and let the scan run its course.
If you ever suspect hard drive failure it is strongly advised you make back ups immediately. When a hard drive goes there may be a point where you can still access your desktop and move files around but that ends very quickly. Final notes on mechanical hard drive failure, There are programs out there which can attempt recovery of data from hard drives that no longer are able to start up. The way they work is by taking out your drive from your computer and placing it into another computer as a slave drive. The other computer is equipped with the software and a trained/experienced operator or computer repair guy of the program may be able to recover some data. Or else if that will not work you could spend thousands upon thousands of dolars for a hard drive transplant procedure which involves a clean room and taking out the actual disk from your hard drive and placing it into another of equal make and model type. Either way, good luck.
Software based data loss...
Lets say a virus is eating away at all your files. It could be risky to connect an external hard drive or a flash drive as the virus may be able to transport itself to that as well. First thing is shut it down and find a computer that has a good up to date working anti virus program. You can use a mapped drive connection with an Ethernet cable between the infected computer and the computer with anti virus to run a scan of the infected computer. If you don't have another computer with good up to date anti-virus or have no idea how to do what i just said then hunt down some one who does or hire a computer repair guy to help with it. IMPORTANT NOTE. If a virus is eating away your files you may see your icons start to change to an unknown type of icon, and as long as your computer is turned on that virus will east away your data. BUT if the computer is turned off then it cant! =D
Chances are if you are experiencing any of the above problems or symptoms you will most likely need to hire a professional computer repair specialist. However a computer repair man is not always necessary if you can catch things in time and have the proper skill to handle such things. Best defense against viruses eating your data is to have a top of the line up to date anti-virus program running. There is no defense against mechanical hard drive failure there is only the "back up plan" =P having regularly scheduled back up programs running on your computer with a back up drive connected can save you alot of headaches and heart aches. Eventually hard drives go bad that's just the way it works.
If you have further questions regarding this article please feel free to ask in the comments section.