For future reference:
I downloaded the manual for your product on this page, and on page 23, it shows H.264 (aka MPEG-4 part 10, aka AVC (Advanced Video Coding)) is only supported in the MOV and MP4 containers (file formats).
You’ll want to losslessly transcode (rip the audio and video stream with re-encoding it) to a container your player supports.
This page has exactly what you need (lossless transcode from MKV to MP4):
Hopefully your audio is AAC-LC, because that’s also the only thing supported in MP4/MOV by your TV.
I just got this new LCD TV, Philips 5000 series (42PFL5604D/78), its a Full HD TV and it comes with a USB port.
On the guide it says that it can read H.264/MPEG-4 AVC.
I have several .mkv 720p files, but it doesn’t play the .mkv files. Which format and how should I convert them to play them in full quality on my TV USB?