You're trying to use your Logitech keyboard to type something but suddenly it has become unresponsive. Don't panic as this is a common problem with several potential fixes. How you fix your Logitech wireless keyboard will depend on what the underlying cause is.
Logitech Keyboard Not Working: Battery
If your Logitech keyboard has stopped working, it may be due to battery issues. Logitech wireless keyboards are supposed to have a pretty long battery life, but this can greatly vary depending on the type of batteries that you are using and how much you are using the keyboard. Low batteries are one of the most common causes for a Logitech keyboard to suddenly stop working. You can fix this issue by turning the keyboard off, flipping the keyboard over and removing the battery compartment. Replace the batteries inside and then turn the keyboard back on. Your Logitech keyboard should start working. If you notice that batteries are quickly depleting on your keyboard then you might consider using higher quality alkaline batteries as these tend to last longer.
The Logitech wireless keyboard relies on a USB receiver to work. If there is an issue with the USB port then this receiver will no longer function properly and, as a result, your Logitech keyboard will not be working. You can typically fix this particular problem by unplugging the receiver and plugging it into a different USB port. If your keyboard now works then you know that the previous port is not working. If the keyboard still doesn't work, try plugging another device into either of these USB ports. If that device works then you know that the USB port is not to blame.
Issues with Receiver
Your Logitech wireless keyboard comes with either a standard USB receiver or a Unifying receiver. The receiver may stop working and this can cause your Logitech keyboard to stop working. You can distinguish between the two receiver types by looking closely at the receiver. If it has an orange box with a black star symbol within it, you have a Unifying receiver. If your receiver does not have this logo then you have a standard receiver. Standard receivers cannot typically be replaced so if yours has stopped working, you will likely need to purchase a new wireless keyboard with a new receiver.
Unifying receivers can be replaced and reprogrammed to work with any Unifying mouse or keyboard. You can purchase a replacement receiver through Logitech or electronics stores online. Reprogram your device by downloading the Unifying software from Logitech's website and then launching it. Follow Logitech's directions on screen to sync the receiver with your keyboard.
A bad driver can also cause problems with your Logitech wireless keyboard. You can fix this by reinstalling the driver. Click the "Start" button and then click "Control Panel" followed by "Device Manager." Double-click the keyboard device and then click the "Driver" tab. Click "Update Driver" to update your keyboard's driver. Windows will search for and install the best version of your driver. If none are found then you can go to Logitech Support to download and install the driver for your specific wireless keyboard. Reboot the computer after installing and your wireless keyboard should be reset and fully working again.