changing default program to open a file no longer works

[pintree3]

On my home computer I decided to change which player opens my mkv files. I went to Control Panel-->Default Programs-->Associate a file type or protocol with a program and when I clicked on a file type and then on 'Change Program' the hour glass went on as if it wad doing its job but then nothing happened. I tried it a 2nd time and still nothing. I rebooted and still nothing. OK off I go to my sister's PC. This time wanting to view my Nikon NEF files there I did the file association with XN view itself but it still opened it the windows default media viewer. Off I went to the Control Panel and do it from there and again the same thing. Since I had used this method to associate files before about a year ago and it worked fine I am now thinking that the Windows updates since then did something to make this no longer work. it is after all using 2 different computers and 2 different types of files which makes me think my deduction is correct. Does anyone have info regarding this and why it isn't working? and what could be done about it? Thanks

 

[TrainableMan]

An MKV is just a shell and can hold many types of A/V files but you may not have the codecs installed to play what the MKV holds.

Do you currently have a codec pack installed? I personally use K-Lite standard but another popular one is CCCP; choose whichever but you should only use one of them.

Note, K-Lite (& likely CCCP) comes with it's own video player which I don't want so I make sure to remove the check from that box so their Media Player does not install. If you want a different media player then for that i highly recommend VLC.