Help needed playing files

I have the older version of the WD media player not the Live one - I bought it 2 years ago. There are a lot of files it won’t play however and I’ve just downloaded a 15gb 1080p mkv file that looks fantastic but theres no sound. I haven’t upgraded the firmware since I purchased it as I don’t have a clue how to do it - can anyone help? Firstly will I need to get a usb to usb cable?

Perhaps the audio is DTS which is not compatible with the WDTV Gen 1. You can use the mediainfo application in order to see your file codecs.

Go to Google and type Mediainfo, you will be able to download the free application.