2010 MacBook DVD player not playing

Assuming the DVDs are not scratched or otherwise defective, the lens or mirrors within the DVD drive could be dirty or the drive could just be defective.

If the DVDs are ejected without the drive trying to read them, then the drive is just defective.

If you hear the drive trying to read the DVDs before ejecting them, then the drive just might be dirty. There are special cleaning CDs with "brushes" on them which are supposed to clean the laser as the cleaning disc spins, but I've never used them since I've always just opened up the drive and manually cleaned it.