Check whether Num Lock is on and toggle it if needed
Try pressing the Fn key with the Num Lock key on a laptop
Restart the computer
Disconnect and reconnect the keyboard
Try a different USB port if using an external keyboard
Replace the keyboard batteries if it is wireless
Turn off Filter Keys, Sticky Keys, and Toggle Keys in accessibility settings
Update or reinstall the keyboard driver
Use the on-screen keyboard to test input
Check for physical damage or stuck keys
Clean the keypad gently
Boot into Safe Mode to test for software conflicts
Run a malware scan
Use an external keyboard to confirm whether the built-in keypad is locked or faulty