Don’t add any extra files onto your device until you cannot figure out how to restore your lost files. You will need to run a scan to check if you can recover your data. For iPhone, if click the Recover tab to check if the files are recoverable. In trying to restore files on your IPod, revert back to the factory settings for the easiest way.
Also before attempting to recover, make sure that the problem is not related to hardware. Check to see if the device is broken or not, as any back up attempts will fail if any repair is needed.
You need to download a software or a programme which you think will help in the recovery of your files. There are many available on the internet. Search for the most suitable one before downloading it. Recover4all is a data recovery software commonly used and it is also user friendly.
Let the programme scan the entire hard drive of your device, be it iPhone or iPod. This can be time consuming but the process will help you recover your data.
If that process does not help, try connecting the device with your computer and let them to synchronize. Click on the Summary tab in iTunes, before hitting on Restore.
Now select the option of restore your previous settings. The data must be recoverable as the files have been backed up on your computer.