Missing Codecs for MKV & AVI Files: How to Check & Fix Playback Issues in Bestplayer or Others

If movies on another computer work properly, first uninstall all codecs you have installed so far. It is necessary to clean the registry of the system - and it will be quite difficult because there are many system codecs and you can quite effectively damage the system. After uninstalling, install only the codec you need, buddy Foxtrott gave a program to check what codec the movie has.
You wrote:

Mayson wrote:

on the second computer, the movies run without any problems

Does the other computer have the same operating system, same recovery program? This is very important information that you did not provide. For example, there is an important difference between the 32 and 64 bit system.

Mayson wrote:

I cleaned the CCleaner registry.

This program is not for amateur use and only works fine if it was installed in the first place right after installing windows. Otherwise, it clears the registers only from safe records. Clearing the registers is done manually.

Mayson wrote:

In fact, others have ceased to be reproducible.

Then you have something mixed up in the system. Simply installing multiple codecs can cause a lot of conflicts between versions (installing different codecs does not overwrite or replace them with a new version)

In this case, since you can't clean windows registries by hand, just reinstall your system and install only one type of codec and only the ones you really need - not all of them. One more thing to consider, many of the players have codecs. There is one more option, install the free 30-day version of PowerDVD, from what I remember, e.g. movies in MKV format were read. If that doesn't help, reinstallation remains.