DVD's created using Windows Media Player.

[ThomasMorris]

DVDs created using Windows Media player don't play on my Toshiba DVD/VHS Combi Rcorder DVR20.

[TheOldMan]

From what I read on the Media Player site

https://support.microsoft.com/en-us/windows/burn-and-rip-cds-235021d5-e1c7-8616-4efd-4f4965fe6b91

From that page it explains

With Windows Media Player, you can burn three kinds of discs: audio CDs, data CDs, and data DVDs.

The DVD's being created are not DVD's per se but a DVD disk with data on it.  While the DVD section of the DVR20 can read certain disks that are not true DVD's by definition, evidently what has been created by Windows Media player does not meet the criteria of the DVD's the DVR20 can read.  A true video DVD that meets what a typical DVD player can read are specific in nature.  A video that is meant to be read by a DVD player must meet certain criteria as set by the DVD video standard, so the information must be "authored" and then burned to the DVD.  Since the OS is Windows 7, you can use Windows/Microsoft Movie Maker to do that.

[WAWood]

@ThomasMorris 

You can look into using Ashampoo Burning Studio free to do this as well -- you can get it here:  https://www.ashampoo.com/en/usd/fdl

[stevecomputer]

You may need to check the type of dvd that is compatible, if the dvd player is older then it may not be compatible with certain types of disk. There are dvd+r, dvd-r, dvd-rw and other types of physical disk and they are not all compatible with older standalone tv/dvd players.