What region DVD gives you problems?
If your player is multi-region,and the disc still does zip,then it could be a player fault.If the player is'nt multi-region,then make sure the disc is the correct one.In the US,and Canada,discs are Region 1.Here in the UK,it's Region 2.As you know,putting a region 1 disc,into a region 2 player won't work,or vise-versa.
Before purchase,always look at the region code on the disc box to avoid any home disappointment.
If the disc plays on your pc,what region have you got it set at.You usually only get to make about five changes,before it "locks" on that setting,so always choose carefully.
Also,try a dvd laser-head cleaner,which you can get from all good stores.This might also help on your player.