When people use the term HDD recovery, it is so ridiculously broad I have to contain myself so I do not chuckle a bit. Basically, that term covers every instance where a hard drive would fail and need to be recovered, for whatever reason. Did you know that a hard drive can actually store multiple different systems at one time, so narrowing down which system caused your hard drive failure is virtually impossible?
But that is nowhere close to the only reason a hard drive would fail. It could be from extreme temperature changes, from hot to cold or vice versa. Even from jostling around the hard drive can cause issues. What most people do not realize is that if they are not a technician, they should not try and complete a HDD recovery on your own. It can literally take one wrong move and it is dead beyond recovery.
If there is data on your hard drive that you want to recover, please leave it to the professionals. At least this way you can be certain that every possible step was taken to recover your data. The professionals are experienced in dealing with corrupt, damaged, and with systems that have been deleted.