http://superuser.com/questions/44079/recover-a-closed-sticky-note-in-widows-7
It is much too easy to delete the sticky notes. Here are two ways to recover:
1) There may be old information left in the file in the App Data directory:
%AppData%MicrosoftSticky NotesStickyNotes.snt
2) If your Windows 7 version supports it, right click on the folder and select “Restore Previous Versions” This is useful for getting back a note from yesterday, last week, etc.
Since clicking the [X] on the note actually deletes it, rather than just closing the note, it can be useful to turn on the Sticky Note delete warning.
Open the Registry Editor and navigate to the following key :
HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionAppletsStickyNotes
Either delete the value PROMPT_ON_DELETE or set its value to 1.