How can I restore file?

On my Mac, there were some failures with hardware or software and the files were deleted. How can I restore them?

This is a tough question, because there a too many of them. To answer the question, one would need to test the tools on the same PC setup with the same settings and the same deleted files. To top it all, some recovery tools may handle well certain types of files (e.g. images), while others - work best with the other file types (e.g. documents).