problem reading dvd

HI: My comp. is not reading dvd. When I put certain discs in the drive. I get nothing. Example. I have a dvd for my singer sewing machine. When I first got the sewing machine, I put the disc in and it came up no problem and I watched it. But lately not working. I put the sewing machine disc in today and nothing. I went to my computer and nothing there either. Can someone help me.
THankyou
Pat