You could try to get in touch with user babo who is a high trusted member of this forum and by checking his profile you can see he offers a wallet recovery service, maybe he could be of help.
There is/was also another high trusted user who performed some good amount btc wallet recovery in the past but I cannot remember the name by hand right now ( will post here if I manageAnyway, it's up to find out who he is)you whether you decide to trust him for 10 bitcoins.

There is/was also at least another high trusted user who performed some good amount btc wallet recovery in the past but I cannot remember the name by hand right now ( will post here if I manage to find out who he is).

Do not fall for scammy services/users ..... Aasuming the story you're telling is true and you haven't already been scammed into buying the .dat file you say belonged to your father...

You could try to get in touch with user babo who is a high trusted member of this forum and by checking his profile you can see he offers a wallet recovery service, maybe he could be of help.
There is/was also another high trusted user who performed some good amount btc wallet recovery in the past but I cannot remember the name by hand right now ( will post here if I manage to find out who he is).

Do not fall for scammy services/users ..... Aasuming the story you're telling is true and you haven't already been scammed into buying the .dat file you say belonged to your father...