Hi, @ImaBassetcase. I'm happy to help you with your concern today.

Please know that there's no option to undo deleted budget in QuickBooks Desktop. What we can do is restore a copy of it if you have one. If you've created a backup copy of the budget and made no changes, you can export it to excel. 

Here's  how:
 

1. Go to the Reports tab at the top of your QuickBooks.
2. Select Budget and Forecast, and click on the report you want.
3. Once you’ve selected the report you want to export, make sure you selected the correct date range under Dates.
4. Click on the drop-down under Excel, and choose to Create New Worksheet.
5. Click Export.

Once downloaded to excel, you can use it as your reference. 
 

You can visit this article to learn how to personalize and filter when running reports: Customize reports in QuickBooks Desktop.

If you have any other questions about setting up a budget in QuickBooks Desktop, don't hesitate to reach back. We'd be glad to help. Take care!