My dvd player is not reading dvds

Hi, I own a dell xps L501x. My dvd player is not reading any dvd movies, disc with data.. and etc. It reads cd though. I insert a blank dvd, it reads the blank dvd and ask me what i want to do. But if i insert a dvd with things on it, it would not read it. If i click on the dvd drive, after awhile my dvd tray will eject and pops up a message asking me to insert a dvd. I check the...