IIRC, extracting a private key from a damaged wallet file requires you to inspect the raw data of the file. Surely it requires a handful of knowledge since it is not a simply job.
There is a reputable wallet recovery service that is known in the cryptocurrency space, Wallet Recovery Services. Take a look at the thread over
here.
According to their FAQs page, they might be able to recover a damaged or corrupt wallet file under certain circumstances. Be sure to check their pricing page, in case it is a match with your budget.
My wallet file is corrupt. Can you help?
Yes, in certain circumstances we can recover information from damaged wallet files.