If the disk itself is working, then use the software recovery methods. When formatting, deleting, viruses, and any number of other problems need to find the disk all the possible structure of the file system and have to build a “tree” – from the root folder as well as individual files. If this is not enough for quality of recovery (for example, if the structure has been overwritten or fatally damaged), then you need to find all the file headers across the surface of the disc to get at least the contents of files, of course losing their names.
In the case of a faulty hard drive is necessary in the laboratory thus “interfere” in its design that he moved to the state in which it can at least somehow “give” the data. You may need to replace a block of magnetic heads, chip on the card, to reprogram the drive to rearrange the plate in an identical drive with intact heads, remove the head from the surface, clean the surface, put the disc into the “accurate” readings and much more. All of these studies can be performed in various combinations, one important requirement – experience specialist. Experience to avoid fatal mistakes, which worsen the situation. In some cases, you can conduct a successful repair of the hard disk so that it save the data.
Deserve special mention instances of degradation of the surface: data from the disk can be read for days with very low speed due to the large number of pereproverok with a high number of failures of reading. The data in these cases, too, can be restored.