Issues playing some .mkv video files

Video files are stored on a MyBookWorld NAS. Up until recently I have had no issues playing any files, however, recently, not all .mkv files will play. I receive a message either that the file format is not supported by the media player or the audio files are not supported by the media player. Yet some .mkv files play just fine. Suggestions?

post a Mediainfo output log

https://mediaarea.net/en/MediaInfo

After installing on your PC … (On your video file right click and open with Mediainfo select View > Tree then File > Export >Text > Save then open the *.txt file and copy and paste the info here)

example

Video
ID : 2
Format : AVC
Format/Info : Advanced Video Codec
Format profile : Main@L4.0
Format settings, CABAC : No
Format settings, ReFrames : 2 frames
Format settings, GOP : M=2, N=30
Codec ID : avc1
Codec ID/Info : Advanced Video Coding
Duration : 3mn 2s
Bit rate : 9 167 Kbps
Width : 1 920 pixels
Height : 1 080 pixels
Display aspect ratio : 16:9
Frame rate mode : Constant
Frame rate : 29.970 fps
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.148
Stream size : 200 MiB (99%)
Language : English
Encoded date : UTC 2011-02-24 20:57:16
Tagged date : UTC 2011-02-24 20:57:32
Color primaries : BT.709
Transfer characteristics : BT.709
Matrix coefficients : BT.709

Audio
ID : 1
Format : AAC
Format/Info : Advanced Audio Codec
Format profile : LC
Codec ID : 40
Duration : 3mn 2s
Source duration : 3mn 2s
Bit rate mode : Constant
Bit rate : 128 Kbps
Channel(s) : 2 channels
Channel positions : Front: L R
Sampling rate : 44.1 KHz
Compression mode : Lossy
Stream size : 2.82 MiB (1%)
Source stream size : 2.82 MiB (1%)
Language : English
Encoded date : UTC 2011-02-24 20:57:16
Tagged date : UTC 2011-02-24 20:57:32