SuperEasy Codec Checker helps you, if you cannot play music, audio files or videos. It is a free, but ad-supported codec checking application that's modern.
Here is a screenshot to illustrate the features and user interface of this application:
Check audio and video files for encoders used so you don't have any problems during playback thanks to this practical app. Screenshot of SuperEasy Codec Checker - 500px · 440px
DivX Codec
FFmpeg
Shark007 Codecs
K-Lite Codec Pack Standard
K-Lite Codec Tweak Tool