Yesterday I watched a DVD on my Acer Aspire 5732Z Windows 7 laptop. When opening the disk on Windows Explorer, there was an option to "Play disk using Windows Media Player." It worked fine yesterday. But today, there is no option to play, and when trying to load the disk through Windows Media Player, the "Play" option is greyed out.

Is there a way to play the disk anymore, and preferably without downloading any dodgy programs, hacks etc. Will VLC work?