If your checkboxes in Excel sheet are not working, explore these troubleshooting steps:

1. Make sure that cells with checkboxes are in Edit mode.
2. Check if there are any duplicate ranges associated with the checkbox.
3. Check if the worksheet Protection is set to Locked or Unlocked.
4. Verify the the correct cell references are entered in the Cell link box.
5. Check if the Workbook is shared and disable it by going to ‘Review’ tab.