restore a corrupted keyboard to its default setting

Use built‑in Windows settings to return the keyboard to a normal, default‑like state before assuming the hardware is bad.

1. Check for stuck modes (Num Lock, etc.)

• If certain letters type numbers or wrong characters (for example U/I/O → 4/5/6, H/J/K → numbers), press Num Lock once and test again. A stuck Num Lock can make part of the keyboard act like a numeric keypad.

2. Reset keyboard layout / language If specific key combinations produce wrong characters or unexpected behavior, the active keyboard layout may be corrupted or incorrect.

1. Add a fresh layout and remove the problematic one:

• Open Settings → Time & Language → Language & region.
• Under Preferred languages, select the language (for example, Polish or English) and choose Options.
• Under Keyboards, click Add a keyboard, choose the correct layout (for example, “Polish” or another layout that matches the physical keyboard).
• After the new layout is installed, move it to the top (if applicable) and remove the old/affected layout.
• Sign out and sign back in, then test the keyboard.

This effectively “resets” the layout to a clean default for that language and often clears corrupted or misconfigured layouts.

3. Test with another user/session

• Sign in with a different user account (or create a new local account temporarily) and test the keyboard.
• If it works correctly there, the issue is likely profile‑specific; re‑adding the keyboard layout in the affected profile as above usually resolves it.

4. If still corrupted

• If the keyboard behaves correctly in firmware/UEFI or on another device but not in Windows even after re‑adding the layout, consider a Windows repair/reset while keeping files:
  • Go to Settings → System → Recovery → Reset this PC → Keep my files → Cloud download, and follow the prompts. This reinstalls Windows and resets settings (including input settings) while keeping personal files and built‑in apps.

If none of these steps change the behavior, the physical keyboard may be faulty and should be tested or replaced.

References:

• Keyboard keys malfunctioning - Microsoft Q&A
• How to reset my keyboard? Combination of "Alt + L " gives weird characters and message is sent automatically. - Microsoft Q&A