Otherwise, right-click on the file and select 'Restore previous versions'.
You'll need to replace with your windows login username and you may need to enable the viewing of hidden files and folders to see the file. If you go too far back, press ctrl-y to redo the undos. You can do this by right clicking on the Sticky Note taskbar button and selecting Close Window. Make sure you've closed the Sticky Notes application before proceeding. If this happened to you, you may be able to recover your note using one of the following methods. Today I accidental deleted one of my sticky notes.
I've been using Windows 7 Sticky Notes for several years now.