Heya, I'd recommend posting on Steam's community page for support on steam specific issues.
I don't quite understand how you managed to delete the achievements. I guess you triggered a console command we used for testing to reset the steam achievements? Which achievements are impossible to get and why?
What do you mean by locking achievements? Do they not register when you complete them?
What does the achievements menu in the main menu say? Does it think that the achievements are still unlocked?
There is an Achievements.sav file in the savegame location (the load game menu has a button to bring it up). If you want to reset your achievement savedata, deleting this file is the recommended way of doing it.