Some users have had success using the lg bluetooth rolly keyboard but this is not officially supported.
Lg tv not connecting to cable box.
Change the tv to the new hdmi input to see if the issue.
Press the smart button on the remote control and select settings option set the universal control on the tv menu press wheel or enter to continue.
Unplug the power to the external device for 30 seconds.
Now please try this.
Shut the tv off and securely connect the cable box hdmi cable to hdmi 1 on the tv.
Bluetooth mice and keyboards are not supported.
Disconnect the cable box from power for 10 seconds to reboot it then plug it back in.
Make sure the other end is secure in the cable box.
Simply connect your usb cable s to any available usb ports on the tv.
Plug the device back in and power the device back on.
Disconnect the hdmi cable from the tv and move it to an alternate port.
Check that the external device is connected to the tv with an hdmi cable and is powered and switched on.
If your remote does not have an input source button press the home button then look in the upper right corner of the tv for the input icon and click it.