What OS & program are you trying to use to play DVDs?
I'm going to hazard a guess at Windows 10 and looking for it to natively play DVDs?
MS took that function away......unless you upgraded from W7 or some versions of W8 where it was included.
If this is new W10, or an upgrade from an OS that didn't have it......it'll cost you $15 in the "windows store"
Otherwise, download VLC Player and use that.