I had braces between 11 - 13 and after the treatment was over i had to put a teeth retainer every night to make sure that my teeth won't move. i used to put it every night but 2weeks ago i lost it. how long can i go without it and my teeth wont move?

Like everything else in your body, everything changes. Tooth position is no exception. There is no simple answer to your question. So, the sooner you replace the missing retainer, the better to maintain your finished orthodontic result.

It's not like putting steel posts into concrete. Bone is a living tissue that changes constantly to resist stress. Guaranteed, if you don't wear your retainers, your teeth will slowly but steadily shift. Go see your Orthodontist before then do.