WOW, that is a powerful demag you have, erased the BD from 15ft-20ft?
Just kidding, pulling your chain.
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No, magnets do not affect any of these mediums, CD, DVD/BD, etc.
I have no idea why it is not playing especially since you tried 3 players now.
Another experiment is to take it to a Blockbuster if you have one near you and see if they would also try to play it, or, at an audio store if there is one near you.