Solution:
1. Open the "Include letters and symbols" option.
As the PIN code of Windows system only supports number by default, it is normal that the system does not respond when you press the letter key in the PIN input interface. To make the PIN code contain letters, please go to Settings > Account > Login Options > PIN (Windows Hello) > Settings. Open the "Include Letters and Symbols" option.
2. Restart the laptop
If the laptop is stuck and unresponsive due to running software, you can wait 2-3 minutes and then try to use it. If you still cannot use it, try to restart the computer to recover it.
Note: If the keyboard fault is not caused by the laptop system jam, you can skip this step.
3. Uninstall the software
If the keyboard cannot be used after you install some software, go to Settings > Applications > Installed Applications, uninstall the software, and restart the laptop to check whether the keyboard can be used.
Note: If the keyboard fault is not caused by software, skip this step.
4. Reset the system
Check the keyboard driver, right-click Start icon > Device Manager > Keyboard. If the Standard PS/2 Keyboard icon displays a yellow exclamation mark, it indicates that the keyboard driver of the laptop is damaged. Right-click this option > Update Driver > Search automatically for drivers and try to update the keyboard driver locally to solve the problem. If the problem persists, reset the system.
5. Visit realme service center for detection.
After the above steps, the laptop keyboard still cannot be used. Please take the device and warranty certificate to realme Book service center to detect whether the keyboard hardware is damaged.