I have the iPhone 4S. This morning, I had 2 unheard voicemails. I attempted to listen to them but no sound was delivered and the progress bar did not move. A few minutes later I looked down and my messages were no longer there. Is there any way to recover these deleted voicemails?
If you did actually delete the voicemail, a new cell should have appeared if you scroll to the bottom of your voicemails.
Then, tap on Deleted Messages, and you should get this screen:
Now, tap on the voicemail that you would like to delete, and press Undelete:
Hope this helps!