Every time I click the "Play" button nothing happens... Help please, what can I do?

Your system specs?

GPU: GeForce GTX 750 Ti
CPU: AMD FX -6300 Six-Core Processor
Memory: 8,00 GB RAM (7,98 GB usable)
System Microsoft Windows 7 Professional

Mmmh... for what I know, your system is fine. You didn't specify your CPU power, but I assume it's over 3.3 GHz.
You could try to take a look at this: https://embed.gog.com/forum/the_witcher_3_wild_hunt/cant_start_game
If it doesn't work, maybe it could be due to your RAM being just as enough as the recommended specs (it's always advisable a little more power to allow the game and the system run without overburdening the system memory), but try to contact support first or wait for someone who could help you better than me ;)

As Nephilim88 said system looks okay,maybe do a check to verify 8gig ram is all good
as it is on the borderline.Even thru windows says 7.98 usable,doesn't mean it's right as
it's only referring to system original setup.In other words it won't tell you if a stick is broken.

But it's won't tell to game either. Right?

Some games yes and some games no.Depends on how clever the game has been
developed.

It's possible you need to repair/reinstall the C++ redistributable.

It's located in The Witcher 3 Wild Hunt/redist/MSVC2012_x64/vcredist_x64

Open that and repair it. I had this issue when I first installed the game and then one time after that as well. Hopefully that helps!

First off... Thanks to everybody. I will test everyting and tell if something works ;)

If the game runs in the background (look in the task-manager) after you clicked the play button you could try this:

Q.: When I start the game nothing happens, but I can see the application running in the background.
A.: There has been a solution circling around that worked for quite a few people, thanks to Hycinthus:

1. Uninstall Galaxy
2. Open command line (Start->type "cmd" -> right click "cmd.exe" and click "run as administrator")
3. Type sc delete GalaxyClientService
sc delete GalaxyCommunication
4. Go to //gamedir\bin\x64 and rename or delete galaxy.dll
5. Launch the game, an error message will pop up, but the next time you start it everything should be fine

Source: http://www.gog.com/forum/the_witcher_3_wild_hunt/faq

Don't forget to backup the save files and game install files first!

Good luck!