Hi,
For us to better assist you with your concern about your login password for your Surface RT, we need to clarify if you are using a Microsoft account or a local account.
If you are using a Microsoft account, you may follow the troubleshooting steps found on this article: When you can't sign in to your Microsoft account to reset your password.
If you are using a local account, we suggest that you download a recovery image for your Surface using a different computer or device.
Keep us updated on the status of the issue. We will be glad to assist you further.
Regards.