Hi,
try:
-If your login information work for https://truckersmp.com/ but you can't login ingame you should try one of these fixes.
-First of all make sure you're logged in with the same Steam account which you were on when you registered at TruckersMP.
-Open notepad or a text editor.
-You need to write 2 rows, on 1st your email, on the 2nd your password.
-Now, copy the email from notepad and paste it in the ingame login screen using keyboard shortcut keys (CTRL+C for copy, CTRL+V for paste Please notice that these shortcuts may be different in your country. If they don't work, please inform yourself how you can do it on Google).
-Do the same for the password.
-Login.
-If the solution didn't work, you must have a strange character in the password that can't be recognized by the login system ingame.
-To bypass this problem, you should change your account password to only latin letters (a to z) and digits (0-9). Please notice that by doing this your password might lack in strength.
-In order to change your password, you must login at https://truckersmp.com/ press Edit Account, insert the new password twice confirm the old password twice and then press save data.
-I hope that one of these fixes worked and you`re now able to login ingame.
If the problem is not solved;
-You can create a ticket. https://support.truckersmp.com/