Addresses that begin with 3 are multisig addresses. Addresses that begin with 1 are single private key addresses.
If you are trying to restore a multisig wallet, such as a 2fa wallet, you can only do that with the seed mnemonic. That is a series of random English words. In the case of a 2fa wallet it'll be 25 words. You have to select the correct wallet type too when restoring a multisig wallet. The correct type is the same type as the original wallet i.e. 2fa in the case of a 2fa wallet or multisig in the case of other multisig wallets. Once you've restored a 2fa wallet it ceases to be a 2fa wallet. All the private keys are now on your computer so it's a single factor wallet now.
Do you have any guide to back and restore it to other wallet because in electrum its always error when i am making a sign message with electrum.. If you are trying to restore a multisig wallet, such as a 2fa wallet, you can only do that with the seed mnemonic. That is a series of random English words. In the case of a 2fa wallet it'll be 25 words. You have to select the correct wallet type too when restoring a multisig wallet. The correct type is the same type as the original wallet i.e. 2fa in the case of a 2fa wallet or multisig in the case of other multisig wallets. Once you've restored a 2fa wallet it ceases to be a 2fa wallet. All the private keys are now on your computer so it's a single factor wallet now.
To restore a 2fa wallet you need the 25 word seed mnemonic. Do you have it? If yes then run electrum, choose file menu > new/restore, give your new wallet a suitable name and then on the next step choose 2fa as the wallet type. After that you just enter the seed mnemonic and set a password. In future if you want to open this wallet use file menu > open.
As for signing messages with multisig addresses you have been told in that other thread that it isn't possible.
