My Tevion DVD has locked me out. I had purchased a universal remote and had set it up then watched a movie from Austrailia (Blockbuster rental). After watching the movie I had pressed some buttons to look at the outtakes,etc. and then later discovered a red key on my front panel! I can't seem to locate Tevion for info and the remote people couldn't help either. I didn't know if the Australia area thing had anything to do with it.
First off, you may need to check the region code of the DVD you tried to play. Make sure that the region code is the same as the one listed on the back of your player.
Even if it is different, I can't imagine that playing a disc of a different region would lock the player entirely. I'd be willing to bet that the lock is from a dealer or child lock, initiated by a key combination you just happen to accidentally discover.
Regardless, you should be able to find information about what the lock is in your manual, and how to disable it.