Sometimes you can pull up a Budget screen and it is blank, and the budget is unlocked:
This is because Show Empty Rows is toggled off, and there are not currently any rows with values in them.
You can click the Options Menu and then toggle on (green) Show Empty Rows and all the Accounts, Business Units or Metrics for the view will appear.
The keyboard shortcut to toggle show and hide Empty rows is the letter E on your keyboard.