If you want a character back - You need an empty character slot and the name needs to be available still (so you can't be using it on another character on your account and no one else can have it either). It also depends on how old the character is and may not always be possible, if the data is completely gone.
I made it so that I don't need to input my password manually again, but since I forgot my password and the password reset phone code doesn't work, I am relying on a method to check my saved password that the GW2 app made to remember.
Be prepared to provide ownership info - I hope you have at least one key/serial associated to the account. Then they might just be able to remove 2FA with that info. (I would recommend authenticator app then. Google already seems to allow backup of the stored accounts there into the Google account / cloud.)