1. Click Application > Accessories > Terminal
2. Paste the below line in the terminal and hit enter
sudo /usr/share/doc/libdvdread4/install-css.sh
3. Enter your login password if asked for
4.Download VLC from
http://www.videolan.org/vlc/ or Ubuntu Software Centre
5. Install and Run VLC (It will be in Applications > Sound and Video)
6. Click Media > Open Disc
7. Click "Play"
Keywords:
DVD won't play in Ubuntu, Ubuntu DVD Player