Sorry to hear you are having this issue.
If I'm understanding correctly, you can log into the forums (duh) but not the game itself?
Here are some things you can try to do
A) Make sure you are typing everything in the same as here. Capitalization matters!
B) If have multiple devices, sign out of all of them before signing back into your main device.
C) Hit the 'forget my password' button and follow the onscreen prompts.
D) I don't recognize your name, so I'm assuming your account is fairly new. If nothing is working and you most certainly can't log back in. Create a new account and restore purchases to recover your purchase of L2.
I hope these work, Godspeed.
Simply put, my job here is to keep the forums afloat through any means necessary