W trakcie instalacji zakupionej dzisiaj gry (Chorus) doszło do uszkodzenia działającej wcześniej aplikacji GOG Galaxy. Brak możliwości uruchomienia tej aplikacji - pojawia się komunikat " Nie znaleziono obiektu VCRUNTIME140.dll" . Brak możliwości uruchomienia gry wcześniejszej (Wiedźmin3) - ten sam komunikat.
Proszę o pomoc w rozwiązaniu problemu.

Reinstall Microsoft Visual C++ 2015
https://www.microsoft.com/en-us/download/details.aspx?id=52685

installation of "Microsoft Visual C ++" failed :(
komunikat : 0x80070666 - inna wersja tego produktu jest już zainstalowana na tym komputerze

you see that error code? 0x80070666

If you search for that using a search engine you can get information about your problem.

It looks like your next step is to try and uninstall any existing/broken MS Visual C++ first.

But you should definitely search that code, it has guides and screenshots and step by step instructions and everything.

Thank you, I will try
The whole problem arose today when I wanted to install a new game purchased on GOG Galaxy.
I have an account and a working GOG Galaxy application with other games. During the installation of the new game, the GOG Galaxy application was reinstalled, and this caused problems with it (I wrote above).
Now it is impossible to run applications, accounts and games.
A window appears with the following messages:
- MSVCP140.dll not found
- object VCRUNTIME140 not found. dll

There several ways to correct this depending on how messed up your Windows installation is;

1. Try first to reboot, and then when starting up again disable any antivirus that might linger, and then install as Admin C++ 2015-2019 redist;
https://aka.ms/vs/17/release/vc_redist.x86.exe
https://aka.ms/vs/17/release/vc_redist.x64.exe

Both comes from https://docs.microsoft.com/en-us/cpp/windows/latest-supported-vc-redist?view=msvc-170 and are official.

2. Try to unregister and register the file;
regsvr32 /u VCRUNTIME140.dll
regsvr32 VCRUNTIME140.dll

3. If that doesn't work, then try to check/repair the Windows installation with (both as Admin)
DISM.exe /Online /Cleanup-Image /ScanHealth
SFC /scannow

The report from each will tell you more about the state of the system files, IF any are corrupted or otherwise damaged.

https://www.intowindows.com/command-prompt-as-administrator-in-windows-10/

4. If that doesn't work you might need to boot up a Linux live usb/cd and manually remove this and possibly other of these runtime files, then up on rebooting, install (again, as Admin) the same redist package(s). Same trick can be used when directx or something else is the problem and the live system won't let you delete or change anything.

Last effort, which sometimes IS required, reformat the disk and reinstall Windows.

Oh, and one more thing, ditch Galaxy all together and only stick to the games offline install files and never look back as Galaxy will bite your behind sooner rather than later. Just ask most people here... Good luck. :D

https://docs.microsoft.com/en-us/cpp/windows/latest-supported-vc-redist?view=msvc-170

First remove all installed versions, next install only supported versions, both 32 & 64 bit

Thank you for all your help and hints.
The problem has been fixed! : D
GOG Galaxy installed a new version to itself, making this fuss. By the way, he cut off "The Witcher III",
but as advised by * sanscript * I play ofline and I don't care about Galaxy. ;)