When you delete any text inside a Notezilla sticky note, press Ctrl+Z to undo. You can even right click inside a sticky note and choose More->Undo.
If you accidentally delete a sticky note, you can open the Notezilla Notes Browser and go to the Trash memoboard where all deleted sticky notes are located. You can then move that note from Trash to any other memoboard.
Also, we have Android and iPhone apps for Notezilla . You can download and sync all your notes from phone too. The automatic sync happens within 2-3 minutes.