If you have previously been able to successfully access Samepage but are now receiving an error message saying that your login credentials are invalid, the user token stored on your device may have become corrupt. This can happen for various reasons, but the solution is very simple. Simply remove that token and log in again.
These steps are best done on a laptop/desktop computer through the browser app (Chrome, Firefox, or Safari). If the issue is on the desktop or mobile app then you can log in to that app after these steps are completed.
Please make sure you know your password before taking these steps.