Hey, I started week ago to play again witcher 3.

And yesterday after 30h of game something gone wrong.
When I am trying to launch GOG - there is notification (attached below, WHY CAN'T I ADD IMAGE TO POST? WTF?)

This is my only account

I already tried
- reinstal old version
- reinstal new version
- delete all and install again
- turn on/off pc

When I am trying to delete rest of folder it's says me that I can't delete this, because this is already open.

At tasc menager there is no GOG Client

I tried to instal it in another location, and another disc - no results.

What else can I do?

You sure about that? Have you ticked the "Show processes from all users" checkbox in the task manager to eliminate the possibility that one of the processes might be hidden?

Sorry to hear you are having this problem. You might want to send a message to the Support team.

Click here.

Be sure, under "Problem Type" to choose "GOG Galaxy Issue".

You can try this :

https://www.gog.com/forum/general/gog_galaxy_beta_starts_now_e5bf1/post925

You could play the Witcher 3 outside of GoG Galaxy. Galaxy is still in Beta; personally, I'd stay away from it.

Not to bash Galaxy, but I never felt like it offered anything I really needed.

ditto

If you need to delete all traces of a program, I have had luck with a program called Revo Uninstaller. In my experience, it will remove all files from a program so you can do a clean re-install. Give it a try, it's free and easy to use.

How to play ourside GOG?
THere is no exe here

I would imagine the exe is in the bin folder. I've seen many games use a bin folder to store executables. But doesn't the game have shortcuts in your Start menu?

Ok I could launch this.
But soon will be new DLC, so i will need GOG client anyway when i buy it.

I again tried to delete all old files, but imposible :/

Try Revo Uninstaller to delete all those old files after you uninstall, then do a clean re-install.

There's no need for Galaxy at any stage, from purchase through to play, of any GOG games (apart from playing in multiplayer for some of them.)

Did you check out what Grargar mentioned? Not being able to delete the files, as well as that message saying Galaxy is running another instance, suggests that it is running under another user.

As I already said - at this PC there is only 1 account. I restarted PC a lot of times and it's still not working.

All the more reason to completely uninstall it (TARFU suggested Revo Uninstaller). If there is no more presence of GOG Galaxy left on your machine then it cannot be running under any user, regardless of how many accounts there are, 1 or many.

Also, GOG Galaxy is completely optional at present, unless you want GOG achievements on the few games that support that, or if you want multiplayer on the Galaxy mulltiplayer platform supported games. The GOG Galaxy software is still in beta and has known bugs and issues. There's a thread about GOG Galaxy with links for you to raise issues (or search existing issues).