My guess is you need some tutorials on how to repair HDD but sadly you won't find any generic ones. The reason is that HDDs can have data loss for several different reasons, and from several different sources that cant be covered by a generic tutorial, but only by a per case tutorial in which case you can google and you will find several solutions for that particular problem.
For example, its different cases when you have a power loss/surge when there is a head crash when there is a controller malfunction if you erased files by accident if partitions got removed if there was a virus, and so on and reach of this problems has its own unique solution(s).
if you have a particular problem, post details about the problem, otherwise, you have to search with google for some info about the subject you seek or even maybe a forum that only focuses on HDD recovery topics.
For Repair software, you can check here
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I will close this since it's out of the scope of our web site but if you have personal issues, PM a mod/admin to reopen it.