I have tried to download voicemail from iPhone to iMac but it says 'Data Encrypted'. When I enter the iTunes back up password it says 'invalid password'.
I then backed up my iPhone to iTunes without encryption and still the same problem.
Thank you in advance.
You should just need to quit and reopen iExplorer which is needed after you manually backup in iTunes. Once you quit and reopen, any unencrypted backup for that iPhone should load, and any encrypted backups should open fine once you enter the password.