When you delete an audiobook from your Kobo app, you can get it back by going to your account archive.

1. Go to kobo.com 
2. Sign in to your account.
3. Select My Account at the top of the screen.
4. Select My Books.
5. Select Archive near the top of the screen.
6. You'll see a list of items that you've deleted from your Kobo account.
7. Find the audiobook you want to restore, and click the More icon under 'Actions'.
8. Select Restore to Library.
   

Once you’ve restored your items, sync your Kobo books app for iOS or Kobo books app for Android to download the audiobook to your smartphone or tablet.