Note! If you have no problems with authorization and you know your game login (e-mail) and password - please log in here on the Support site with your game account before sending the request - it will help us to solve your problem faster!
You are able to log in to the game or to Warthunder.com website by using an https://store.gaijin.net/ account because these accounts are completely the same.
Please, pay attention that Login and Nick may be different. Login is an E-mail address in most cases.
If you forgot a password you can recover it.
To change a current password you can go to "My profile" section at https://store.gaijin.net/ . Follow a "Modify profile" link, then check an option in "New password" section which allows to set your own password or generate it automatically. Automatically generated password will be sent by Email.
Firewall may also be a reason. If you have previous successful log in attempts you should check firewall exceptions and re-install exceptions for the game.