Greetings, Sanchago0.
If you played in the Red and Blue servers, you will need to merge your account's progress so as to be able to play in Silver Server. Both of these servers merged a few years ago. You can merge your account in the dashboard. Choose the story progress of the server you want to keep. Pokemon, items and pokedollars will merge together into Silver Server.
To read more information about merging, you can check this thread which will help you out in the process. After you merge your account, reset your password and you should be able to play once again.
If you have any other questions, please do not hesitate to ask them.
Kind regards,
Kvar
