I had an account in this forum for some time (recently even my trustlevel was promoted). Strangly enough, today I could not login anymore and had to recreate the account (same username @tobias but different email address).
Can anyone of the @CS-Cart_team let me know what happened there?
A few months ago CS-Cart forum has switched to the different software. Most of the users, however (including us) did not lose their accounts.
I assume that you tried to use “forgot password” option to check if your old account exists?
You should write to the forum administrators and give them as much info about your account so that they can check what happened with it.
As @soft-solid correctly stated, the forum was moved to the new platform last summer. Unfortunately, too much time has passed since then for us to be able to tell you exactly what happened to your account. However, I must say that if this nickname was free, it means that the account with that nickname either did not exist or was deleted for some reason.