Here’s my experience in case someone else is still looking for solutions. I went through a similar situation with an old HDD from a Windows 98 system and tried all sorts of software I found online, but with no real success. In the end I turned to Salvage Data, and they managed to recover over 90% of my files, including work documents that seemed completely lost. The process isn’t the cheapest, but I found it fair and transparent – you send in the drive, they do an evaluation, and you only pay after you confirm the recovered data.