Songs you delete from your OnSong library that are not loaned are marked for deletion. You can view these songs by tapping on the gear icon in the Menubar top open the Utilities Menu. Next choose Tools and then Undelete Songs. This displays all the songs that have been marked for deletion. You can then place checkmarks next to the songs you want to undelete and tap on the Undo button in the upper right corner.

Songs in your Undeleted Songs list remain in that state until you clean up your library. This tool will remove any deleted songs from your library as well as perform other functions for reducing the library size and enhance performance. To do this, tap on the gear icon in the Menubar to open the Utilities Menu and then choose Tools and Cleanup Library. Please pay attention to the series of prompts. For instance, you may be prompted to delete imported files that you have since converted into text-based chord charts.

Once this process is completed, the deleted songs list is cleared and you can not restore those songs.