Hello,
First of all, could you specify which firmware version you are using? If it is not RUT2XX_R_00.01.14.3, please upgrade your router (it will help to avoid old issues that are already fixed in the latest release). If I do understand correctly, you are able to access the router WebUI but when you try to log in it displays an error that the password is incorrect, right? Could you try to reset your router to factory default configuration?
Regards.