Back when I was using Windows 98 and XP, codec pack is the first thing that I will install after completing the driver installation. These codecs are required to play downloaded videos and sometimes even audio files or else you might end up hearing the sound but no video and vice versa. The only codec pack that I used before is K-Lite Codec Pack and I never had any playback problems with it. As for now, I have not installed any codec packs ever since I started using media players such as VLC media player and KM Player that has built-in codecs. Moreover most of time I watch downloaded videos in my WD TV Live player and not on my computer so there is no reason that I need to install any codec packs on my computer.
What I’ve learned last time was codec packs are very sensitive. After installing it and if it works perfectly, just leave it as it is and there is no need to update the codec pack. Reinstalling codec packs because of some playback problems may not even be advisable. You should probably try to use a tool called Codec Tweak Tool to scan the registry to detect and remove broken references to codecs and filters first.
Actually Codec Tweak Tool is already included in the K-Lite Codec Pack. If you don’t have K-Lite Codec Pack, then you can just download this portable and free tool to help you detect and remove broken codecs and filters. It comes with a very simple and straight forward user interface with a couple of buttons such as Fixes, Reset settings, Various tweaks, Backup settings, Manage DirectShow filters, Manage source filters, Thumbnail settings, Generate log, Speaker configuration, DirectShow filter configuration, Restore settings and Manage ACM/VFW codecs.
Most of the buttons there will probably confuse you if you are not familiar with codecs. So the best option to attempt fixing codec problems is to click the first button “Fixes” followed by detect and remove broken VFW/ACM codecs and DirectShow filters. Do not worry if some of the buttons in Codec Tweak Tool are grayed out or disabled. It merely meant that there is nothing to configure for that section.