Windows essential media codec pack its a free open source software if yo download and install this software you can get rid of such kinds of problem. After install you can play all kinds of format video and audio player in your PC.
Now lets take a look what kinds of format video and audio format can be run here: MP4, MPEG-1, MPEG-2, DivX, XviD, Vorbis, AVI, 3GP, AAC, AC3, APE, AVI, DivX, 3ivx, DAT, h.264, x264, Nero Digital, DTS, FLV, FLAC, HD-MOV, MPEG-1/2, M4A, MP3, MP4, MO3, MOD, MKV, OFR, TTA, OGG/OGM, S3M, Vorbis, VOB, XviD, XM, WV, UMX and many more. It can run CD and DVD directly. It can be used in Windows 2000, XP, Server 2003, Vista or 7. Download link:Windows Essentials Media Codec Pack