Hello @fannykrejci19,
How are you? I hope everything is alright.
This is your TruckersMP account: TruckersMP Profile Link / Steam: Steam Profile Link
If you are using a new Steam profile, you will need to create a new TruckersMP account. If you do not remember the account details mentioned above, you need to contact TruckersMP & Steam Support to regain access if you have lost it.
I hope this helped you, have a great week.
With Kind Regards,
Almeida'