Losing data usually occurs by accidental misplacing a file or by a virus or malware. Usually I can remove viruses or malware remotely.
If the hard disk physically broke down, usually caused by hard shocking movement of the disk, heat, thunder or just wear and tear, most if not all of the data can be recovered by me.
Afterwards the Hard disk will need to be replaces and Windows re-installed.
If your data is misplaced do a computer search for the file.
If it was accidentally deleted and it is not in the wastebasket anymore, last resort is file recovery software. However make sure to use the computer as little as possible, not to override the file.
A deleted file is not really deleted, only the reference to tat file is. The space occupied by the file can now be reused by other files.