Why does my iPhone 8 Plus Keyboard won’t work, display boxes instead of letters and how to fix it?

Problems like this are frequently caused by app bugs. It can happen if you make a mistake with your iPhone's keyboard settings, install a new update for the keyboard app or iOS, use the phone while charging, or have your screen replaced. The majority of reported incidents are software-related, implying that end-users may take steps to resolve the issue on their own. If you're having difficulties with the keyboard app on your iPhone 8 Plus and want to troubleshoot it, follow the steps outlined below.

1. Solutions
   Some programs that are left running in the background may crash at any time, causing conflicts with other apps on your iPhone. These programs aren't running, but they're on standby. While this may be required, particularly if you wish to multitask and want to navigate through apps quickly, sometimes keeping multiple apps in the background can cause other apps to glitch.
   On your iPhone 8 Plus, here's how to force an app to quit or close:
   
   
   1. To see your most recently used applications, double-click the Home button.
   2. To close the app, swipe up on the preview.
   Restart your iPhone after closing all background apps, then launch the app to the keyboard app to test whether it now works as planned.