Press the keyboard lock shortcut if your device has one
Try Fn + F6, Fn + F8, Fn + Num Lock, or Fn + Esc
Check if Filter Keys or Sticky Keys is enabled and turn it off
Restart the computer
Unplug and reconnect the keyboard if it is external
Try a different USB port
Replace the keyboard batteries if it is wireless
Turn the keyboard off and on again if it has a power switch
Update or reinstall the keyboard driver
Check for physical damage or stuck keys
Unlock the keyboard from the device settings if it is a laptop touch keyboard or accessibility lock
If the keyboard is still locked, test it on another device