DVD not play because .ppt format.how does rectify?

Answer 1

The DVD you are trying to play is not of a Format that your machine can read.
This happens a lot with 3rd party Homade Disc's when users don't know what setting to use when burning.
It can also happen using a Media that is not compatible with your machine.
I suggest you learn the differences.
http://www.videohelp.com/dvd
Don

Answer 2

Files with a .ppt extension are Microsoft Office PowerPoint files. You will need either PowerPoint, or a free PowerPoint viewer from Microsoft to view the file.