Can not detect video DVD

Try cleaning the surface of the DVD. For a cheap fix breathe heavily on the back side of the DVD, the one which is reflective and has no writing or images on it, then while it is foggy start to move a piece of cloth or your T-shirt from the center hole outwards in one motion. Repeat that until you have cleared the whole DVD. If that does not help, check to which region your DVD is locked. Look for an elliptical image of a map of the world with a number in it. Check if your DVD drive can open DVDs encoded for that number. And if all that fails, open the DVD case and lightly clean the laser lens with something like a moist cotton swab.