I created the keys file sometime around 2016-2017. It doesn't have a password. It was originally named "wallet".
I renamed it to "monerowallet.keys".
I open the latest official Windows GUI wallet, click restore wallet from keys file.
It asks for a password, I leave it blank.
The error says "couldn't open wallet: internal error: failed to deserialize keys buffer".
I don't have the mnemonic phrase. All I have is the keys file.
Should I try using the Linux wallet? It might give me the same error. I have Linux but never use it, are there instructions?