Hi
The forum and the server are two separate elements
You cannot use your game account to log into the forum, only if you have subscribed with the same username and password.
If you have forgotten your in-game password, you can reset it using the reset tool available in the user menu:
- CoD2MP_s 2020-10-17 17-16-37-32.jpg (45.93 KiB) Viewed 8758 times
You can also create a new account, I saw that your account is at level 13 which is very easy to redo.