If the keyboard is not working now, please try to use USB external keyboard 

Reinstall your keyboard driver. Click Start and type device manager. A new window will appear, look for Keyboard and expand. Right click the keyboard device and select Uninstall device. Restart your laptop and see.

If the above method did not solve the issue, I'm afraid this is a hardware issue and the keyboard is faulty. You can try to bring it to your trusted technician to be replaced, or you can use an external keyboard.

Sorry if this is an obvious question but did you try replacing the batteries in the keyboard? Also not knowing the model of the system you are using, it could be a problem with the Bluetooth receiver.

Worse case scenario, replace the keyboard as the KM3322W (the KB3322wt replacement) is rather inexpensive.

EDIT: This is a bit of a trick question as it was posted in the laptop forum but in fact this is a Dell wireless keyboard and the system it is used with was not specified.