@Bart *************
doesn't work like that, and
I would bet dollars to durian that the O/P doesn't have an ED VISA, but instead has an extension of stay (they would look at the stamp in their passport).
Leaving without cancelling an extension of stay doesn't officially cancel it with the immigration office that issued it,
True, it stamps you OUT of thailand, but if you come back and go to get any type of long term extension they'll see you have an "open extension" in your passport (even if it expired months ago, it was not cancelled correctly)
people have and do get fined trying to get new extensions on other visas for not doing it the right way before they left the last time.