Is it the last song that you want to save or the others? If you only want to be able to access your other songs, simply reset GarageBand from the "Setting" app.
Open the "Settings" app, scroll down to "GarageBand", click it, and toogle the "Reset GarageBand" button to "On".
The next time you open GarageBand, you will be able to pick another project to start your work, but I have not much hope, that this will allow you to open the problematic project.
Have you set your iPad to backup to iCloud and is GarageBand included? Then you may be able to restore the last version of the project by restoring from the backup.
It is a long shot but try the following.
- Export the GarageBand Song (the project not the mixdown) to iTunes via iTunes File Sharing.
- Grab it from iTunes and put it on your desktop.
- Rename the Project file in the Finder and then put it back into the GarageBand iTunes sync window
- Now in GarageBand, import that Song back in the My Songs window using the Copy from iTunes button.
- Now try to open it.
This procedure might help if the original GarageBand Song has some bit that get stuck and corrupts the file.
Hope that helps
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