- Close the file without saving it
- Open the file in Notepad and check for the leading zeros. If they are still missing, use your original file that contains the leading zeros. If that is not available, manually add the leading zeros in Notepad and use this file in the import.
To prevent this from happening in the future, either:
- Refrain from opening the data file in Excel
- Open the file in Excel using the Text Import Wizard. For instructions, refer to How to prevent leading zeros from being dropped in Excel (16061).