Keyboard isn't working
If your K400r isn't working, the problem is likely a lost connection. The connection between the keyboard and the Unifying receiver can be lost for several reasons, such as:
- Low battery levels.
- Moving the receiver from one USB port to another.
- Moving the receiver to another computer.
- Plugging the receiver into a USB hub, KVM switch or other unsupported device. (NOTE: Your Unifying receiver must be plugged directly into your computer.)
- Using your keyboard on metal surfaces.
- Radio frequency (RF) interference from other sources, such as:
- Wireless speakers
- Computer power supplies
- Cell phones
- Garage door openers
Before connecting your keyboard:
Fix or rule out the potential problems listed above.
Insert new batteries (see answer 36022 for instructions).
Turn your keyboard on (see answer 36024 for instructions).
Make sure the receiver is securely plugged directly into a working USB port on your computer.
Turn your computer on.
Reconnecting your keyboard
Download and install the latest software from the K400r Downloads page.
- Launch the Logitech Unifying Software:
Windows: Start > Programs > Logitech > Unifying > Logitech Unifying Software
Windows 8: Start screen > Logitech Unifying Software
- Click Next at the bottom of the Welcome screen.
- Follow the on-screen instructions to turn your keyboard off and then back on.
When your keyboard is detected, you'll see this window:
If you can type in the testing box, select Yes and then click Next. Otherwise, repeat from step #4.
Click Finish to exit the Logitech Unifying Software. Your keyboard should now be connected.
If this solution doesn't work after a couple of attempts, restart your computer and try the reconnection process again.
Keyboard frequently loses connection
If your keyboard frequently stops working and you keep having to reconnect it with the Unifying receiver, try these suggestions:
Keep other electrical devices at least 8 inches (20 cm) away from the receiver.
Move the keyboard closer to the receiver.
Try the receiver in a different USB port on your computer.