We have some problems with your product. I need a service manual to check for potential problems, so can repair it ourselves.

Unfortunately, we do not provide technical manuals to end users, you can contact customer support for assistance.

I cannot find the KB-G235/KB-G255/KB-G265 driver to configure the multimedia keys, other keyboards have drivers to easily manage those keys.

This is a plug-n-play device, it uses the Windows default driver. Check the manual for which keys to press to access the multimedia keys. If you still have a problem, contact customer support.

Sometimes I have to reset the computer to make KB-G265 work. I tried to download drivers from your site, but there are not any, why?

KB-G265 only works with Windows, but not Mac.
It is a plug-n-play device and uses the Windows default driver.
Try to plug into another PC or USB port to see if the problem is the same.
If yes, the problem is with the USB port.

I have KB-G265. After a short time, there is a problem with the left corner Ctrl key, it does not work and blocks. Why?

It should not block when you press the Ctrl key.
Contact customer support for assistance if your model is under warranty.

What is your global warranty on your products?

Unfortunately, we do not offer global warranty on our products.