My game + exp set have disappeared from libraries from website and galaxy

What games were in Library?

You probably did not buy the games directly from gog. Which is never a good idea, since other sites are not officially supported, so not legit. So your keys are probably deactivated because of fraud:
https://www.gog.com/forum/general/3_games_disappeared/post15

From FAQ:

I have paid for a game but it isn't listed on my account? What now?

There are two possible causes of this issue.If you never saw the order success screen after paying, and have received an order confirmation e-mail, then your user account may not have been refreshed properly, due to increased server load or a temporary website glitch. To fix this, follow this link: https://www.gog.com/user/refresh. This should only be required once.If you never got a payment success screen, nor an order confirmation e-mail, and you're sure that the payment went through, please contact Support. It's possible that there was some problem with the payment, and we need to process the order manually.Such cases are our #1 priority as far as Support tickets go, so we should be able to resolve ths very quickly.

May I ask you where you bought your game?

on gog

Try this link: https://www.gog.com/user/refresh

If this doesn't help open a support ticket.

proof

I believed you. But if the account refresh doesn`t help you need to contact the gog support: http://www.gog.com/support/contact
We, the members of the forum, can't restore your game.

Is Witcher 3 the new Fallout?

Yep. Support fixed it.
It took a few hours though.