Unfortunately LG Keyboard has stopped, as the error itself tells us that the keyboard has stopped we know we have something gone wrong. Based on experience, this issue usually originates from a software glitch. This error is not hardware related, and can be resolved by stopping and clearing the data on the LG Keyboard app. If clearing data and changing the keyboard does not works, then it would be worth doing a hard-reset.
The instructions for hard-reset varies depending on the model of your phone; so i’d suggest doing a Google Search or reading the manual that came with the phone.
Clear Data and Restart the LG Keyboard App
Go to Settings
Under Settings > General > Apps > ALL (scroll left of DOWNLOADED/RUNNING options near top)
Locate “LG Keyboard” and a button that says STOP and CLEAR DATA
Click stop, then clear data.
Test if the keyboard is now working, if not proceed to Method 2
Change the Phone’s Keyboard
Tap Input Language and keyboard Layout
Choose On screen keyboard settings
Change QWERTY Keyboard to Phone’s Keyboard.
Test and see if that fixes the issue. If not then it would be best to do a hard-reset and if the hard-reset doesn’t solves the issue, then i’d suggest sending it to the manufacturer for a warranty repair. If it is out of warranty, then it’s probably has lived it’s life and now is the time to replace the phone.