If you don't know what was the address you used when receiving bitcoin, copy and paste all private keys into electrum. One of them should be associated with your address.
If the address starts with "bc1q", you need to apply this when importing:
How To Import Segwit WIF ~ to Electrum ~
For P2WPKH addresses (Bech32, starting with 'bc1')This time we'll add
p2wpkh: in front of the private key.
For example
p2wpkh:5PrivateKey
This should generate the corresponding Bech32 address
There are approx 70 keys, I don't understand which one I should use "]p2wpkh:5PrivateKey".
Again, sorry for being such an ....
Kind regards,
Martin