I know with one hash of my wallet you can hack it and get all my money.
Actually, that isn't true. By design, the extract script that btcrecover uses for Electrum only takes a very very small extract that cannot be used to access your wallet unless the person has the entire wallet file. The whole idea is that you can freely give the extract without worrying about loss of funds. The only info that someone would have is your password (assuming they were able to recover it).
Without access to the rest of your wallet file, it is impossible the decrypted header information could ever lead to a loss of funds.
I just need to know how to use btc recover to recover just one letter of my password.
You can't... It either finds the whole password or nothing at all. The password itself is not stored in the file, it's just used as a key for the encryption algorithm used to encrypt the wallet file and wallet file contents. So, you need the whole password to be able to test if it works.
Your options are basically:
1. Trust a wallet recovery service (give them extract or wallet file), pay fee
2. Brute force the password using btcrecover (or maybe hashcat)
3. Remember your password
4. Find the correct seed for your wallet in your records
If you remember anything at all about the password, you can significantly reduce the number of passwords that btcrecover will generate by creating an appropriate tokens file
2 : try it doesn't work. I don't know how to make a good token file with my password and to make btcrecover try my password with some change.
20 chars, i think just one letter or one number is wrong or not is in place.
3 : I know my password. It doesn't work. Something goes wrong when i type it. One letter or one number is different.
4 : The correct seed. I even recover one of my btc adress and i check it i can find it on receiving adress. So this is the correct seed.
I had the same problem on Multibit.