Answer to: Photos disappeared when battery replaced. Can they be retrieved?Hi, the first thing I will suggest you to do is not going to search method on Google to restore your photos, but stop using your iPod Touch to take any new photos, video, audio, also don't put any new photos, video, audio into your iPod Touch first. You need to keep the suggestion above 'cause you still have a chance to retrieve your lost photos. But if you do the things above (means you put the new files into your iPod Touch), you may lose your chance to recover your photos. Actually it's not so complicate, I will explain it for you. When you delete a file (no matter this file was deleted from iPod Touch, storage device like USB drive or other device, computer hard disk), this file is not really "gone" forever. The operating system only frees up the space which is taken by this "deleted file" so that the space can be used by the new file. Let me tell you like this: You delete "A file", the space of A file now is available for any other files. If this time you put a "B file" into the device which the "A file"
Answer to: Hard drive crash, how to recover content?Yes you can get your files back. But I think the most important thing you need to do is to fix your crashed hard drive. Once your hard drive is repaired, you can consider to find ways to recover your lost files. But one thing you may need to pay attention is that after repairing the hard drive, you'd better not put any new files into you drive 'cause this may lead to the data overwritten. Once the data overwritten happens, you will lose the chance to recover files. You can have a look at this post to see if it can offer you some useful tips for solving the problems: http://www.uflysoft.com/data-recovery-mac/mac-files-recovery.html
Answer to: Recover data from external driveHave you put anything new into the drive after the files were deleted? If yes, the chances of file recovery will be reduced than usual. If not, you can recover the files even all of the files were deleted. But you'd better make sure of this: After file loss happened, stop using your device like your external drive or your computer (the device is where your files were lost from.) This is a post you may need if you want more details about data recovery no matter you lose your files from your computer hard drive or external drive: http://www.uflysoft.com/data-recovery-mac