When I tried to play a DVD on my laptop, I tried to open WMP but it didn't open. I did leave the DVD in my laptop for a fortnight but when I played it a week ago it was fine and my DVD drive is reading the DVD so I think that's ok. I tried to make sure WMP is up to date and it was working fine until a few days ago. I can't think of any triggers for this and when I tried to uninstall it that didn't work either as I couldn't even find it in the programs list. I then tried to install a different media player (GOM) but that didn't play my DVD either although it did play music fine. I am really concerned - should I just get a new laptop? Or is it worth getting it fixed?
Try another DVD, if it works then your DVD (disk) is probably just bad.
Test the DVD drive by booting from a bootable DVD. If that works, then it's probably your OS (and not the drive). Try a System Restore to a point before you started having the problem, if that doesn't work, try a reinstall.
If the drive is broken, then whether to replace the drive or replace the notebook is up to you, and your budget. :)