Why those files are in C and not in the installation folder, is very strange.
Every time you loose OS, you loose and the wallets.
I have to admit, Electrum seems like complete garbage.
And that's what the seed phrase is for.
Most wallets including Bitcoin Core does it too, it saves the wallet in the data directory which defaults to the same upper directory as Electrum's.
In fact, most applications does it, Games don't save the savedata in the same game directory, etc.
The most probable reason is if the user decided to uninstall or update, the wallets and other user data wont be overwritten or deleted.
What are BIP39 and SLIP39 seeds? Should I try with them?
Both options aren't available when creating a new wallet.
Those will only show during restore (
I already have a seed phrase).
SLIP39:
https://github.com/satoshilabs/slips/blob/master/slip-0039.mdIt's basically multiple seed phrases from your BIP39 seed. It should be provided with enough required shares to be restored.
"
BIP39" checkbox forces BIP39 derivation to the seed phrase which changes the default passphrase from "
electrum+extension" to "
mnemonic+extension".
But unlike in actual BIP39 wallets, Electrum wont enforce the checksum or wordlist, only displays if it's valid or not; even invalid seed phrase can be restored.
So unless did something 'special' during wallet creation like going from "
create a new seed" (
copy) to "
I already have a seed phrase" to enable the checkbox, you wont have to bother with this option.
Note: Some users do that to generate P2SH-SegWit with Electrum.
Any idea what's going on?
How old is the wallet file?
Do you have a screenshot of the original wallet that shows the wallet type next to the wallet name?