How to restore transaction sheet? Header row deleted

I accidentally deleted the header row on the transaction sheet. Which means, none of the data is being pulled to report sheets. How can I restore the sheet / fix this?
Note: I tried to just “add a row”, and then fill in the column titles, but this doesn’t work because the category column is formatted for dropdown menu, and I can’t figure out how to undo this.
I also went to the templates in the feed add ons to restore the template, but there is no option for restoring the “transaction” sheet template. Thanks very much for your help.

If you are using Google Sheets, you can revert to a previous version. Look for Version History under the File options.

Restore to a previous version. In Google Sheets, File > File Version > See Version History. And then restore to a version before things got messed up.