When you delete a sticky note in Notezilla , it goes to the trash memoboard. You can retrieve the sticky note from there. Please go to the trash memoboard. Or you can search for that note using Notezilla 's search option.
Once you go to the Trash memoboard, activate the sticky note to be restored, right click on the title and choose "Restore note" option from the menu.
If you have permanently deleted a sticky note, even from the trash, then you can restore one of the backups from an older date using the Notezilla Troubleshooter tool.