SONY DVD RW DW-U10A plays cds but not dvds

The title says it all. It plays all cds I shove in it , but it won't play dvds that I've bought or made. Why does it play only cds?

From the sound of things the superdrive must be in s MacBook, MacBook Pro, iMac or Mac Mini. These all use slot loaders which have a very high failure rate alas.

Sony dvd rw dw-u10a

This dvd player is a tray loader in a powermac G5 1.8 pci.

CD and DVD use different sized "grooves" for want of a better word, and quite often this happens when the laser is failing, or it may be that it's just dirty.
Blowing air onto the laser lens can clean it, or a disc based cleaner can work (others don't like them, but I have had no issues with them).
I would try cleaning the laser anyway.

After Kevriano's suggestion, the superdrive is failing. It is eight years old now. Simple job to install a new DVR in a G5 PowerMac.

In fact actually the superdrive uses two DIFFERENT lasers to read CDs and DVDs, and one of the lasers has either failed or is dirty.

But I agree with harryb2448 -- it's not worth futzing with unless a quick dap of compressed air fixes the issue, just replace the thing it's long past its prime and very cheap to replace.