Coby DVD shows Invalid Disc HELP PLEASE

Did you make the disk if you made the disk your computer has to give it a digital signature so the DVD player can read it if you're using a regular DVD then I would very carefully using rubbing alcohol and Q tip clean the actual laser I would be very careful doing this if too much rubbing alcohol is on the Q tip it will ruin the laser you can also try resetting the DVD player by taking out the battery and unplugging it from any power source and leave it that way for at least 20 seconds to a minute if that doesn't work you might have something else wrong

Whenever i put a dvd in my dvd player always says invalid disc

This happened to me, insert a disc and it displayed "no disc". Tried cleaning it as stated above but that didn't help, resetting didn't help either. Showed it to a buddy and we noticed that when we opened the player it would spin a little. His trick, open the dvd player, push down barely, not enough to close but just enough to get it spinning. About 10 seconds later, the movie popped up. Again, if you push down to hard it will close and read no disc, let up to much and it will read open disc.

My coby portable dvd player is showing invalid key on screen, what does it mean??