You should be able to go here: http://forum.simutrans.com/index.php?action=profile;area=account
Check the first drop-down box.
If, for some reason, you are unable to get there and correct the language, please reply here and I'll get to you ASAP. If you don't specify your language, it'll be set to English. :)
If you try to change the language in your profile settings, you will get a message (perhaps in Albanian) to also enter your password to make the change. It is the last entry on the profile page. Fill out this field and save again in this case.
Yes, I had this problem: I had to use Google Translate to understand the Albanian text enough to get back to English.