I know I also have at least one instance of electrum on one of my old disks
Electrum's wallet file doesn't have a strict naming system, it can be named anything and it doesn't have an extension like "
.dat"
The default names are "
default wallet" for the first, "
wallet_ 1" for the next, then "
wallet_2" and so forth.
But if it's from a very old version, look for "
electrum.dat" file.