acheivments disapeared

[Catidermy]

i had almost all of them and excited out to look at a guide, and when i rebooted steam id lost all of them except for the one for opening the developer console....

[Darklizard]

You probably accidentally clicked on the 'Reset Steam Achievements' button in the dev console menu. It's really easy to do, since it switches out the 'Show Steam Achievements' button and does not ask if you really want to do it.