How to Fix "Internet Explorer not playing audio or video files"
The reason for the error is because your defaults have changed to a third party program for playing your audio and video files.
1. Click Start, select
Default Programs 2. Click
Set program access and computer defaults 3. Click
Custom, and select
Windows Media Player 4. Click
OK.
5. Click
Set your default programs 6. Select
Windows Media Player from the list
7. Click
Set this program as default 8. Click
OK.
Note: Also configure third-party player so that it does not takeover the media file associations again.
Internet Explorer not playing audio or video files 
