Perhaps using the term repair when referring to hard drives is not entirely accurate, as your number one priority is actually to recover all of your valuable files rather than fix the hard drive itself. If your hard drive is either in the process of failing or has already done so, making sure that everything you have stored on it does not get permanently lost is certainly what is most important to you.
There are a number of methods which you can use to do this. One method is the process of getting all of your files backed up onto another source for storage, if you have not already done so; then you will be able to transfer them onto the new hard drive that you purchase to replace this one. However, one reason this is not the most ideal method is that if your hard drive is in the process of failing, you have no way of knowing how long you have before it will refuse to work at all; you may not have enough time to complete this process while your hard drive is still functioning.
Another method is to copy your disk image. This method will make it much easier for you to keep track of everything that you have stored on your hard drive. If you decide to make this type of copy, it can then be stored on a CD or other source for effective retrieval.
If time does not allow you these options and your hard drive fails with no back up, you still do not need to give up, because consulting a professional is almost certain to bring you the results of fully recovering your data. Although there are a number of services available which sell software for computer users to attempt this process themselves, if you want the most satisfactory results it is best to leave this method to someone who has the qualifications necessary to be able to do it correctly. You have much invested in your hard drive; surely you want all of its stored data to be in the care of someone who can get it all back to you.
The very best way of dealing with hard drive failure is to already have all of your files safely stored on a back up source. It does not take much time or computer know-how to be able to do this. It will certainly eliminate all of the difficulties involved in scrambling to save data while the hard drive is losing its capacity to function, or, even worse, not being able to save them at all. However, in the event that it does come to the point of needing to recover files from a hard drive that has stopped working altogether, the best way to go about it is to save yourself time and needless aggravation by giving the component to a specialist to do this delicate process for you. If your hard drive has already quit, you want the best possible service for data recovery.