This player came bundled with Windows 7 proffessional OS. I do not know how to check whether this is Windows Media Player 12.
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Open Media Player and go to...Help / About...to find
version number.
Media Player 12 should play MPEG 4 files but if not...
you could try downloading and installing a codec pack.
No guarantees...but maybe the following codec pack
would be worth a try:
(FWIW...it's always a good idea to create a System
Restore point before installing software or updates)
***Proceed At Your Own Risk***
Windows 7 Codec Pack
http://www.windows7codecs.com/
Download From:
Windows 7 Codec Pack
http://download.cnet.com/Windows-7-Codec-Pack/3000-13632_4-10965840.html
(filename to download : "codecs.for.windows.7.pack.v4.0.5.setup.exe")