Lenovo W501 does not see the hard disk

Invisible disk
Sometimes it happens that computers do not see the hard disk, it does not mean that it is not in the middle, the reasons for which the computer displays this message may be a few, in order, however, to find out what type of failure we deal we should follow steps:
1. enter the BIOS by pressing Ctrl + ALR + F3 and we check to see if the drive is visible.
2. we download the data from the disk using the suitable programs.
3. we carry out the deep formatting the disk enabled from the level of BOIS-a.
4. if the deep formatting proves ineffective we should remove the disc and replace it with a new one – undamaged.