Will only play cd not dvds. lens turns red

HELLO
This sounds very much like a laser problem. ALL DVD players have a dual laser (one for CD other for DVD). It is very likely that the DVD laser has gone defective that is why you can only play CD's.
Another thing you can try is to clean the laser lens using isopropyl alcohol and a cotton bud - laser may be dirty/dusty as this can cause problems too.
If after cleaning the lens you can still only play CD's, then the laser will be defective. This will be an expensive repair job therefore it's cheaper to buy another unit.
ALL THE BEST (:-)