If you lost data on an iPhone, i.e. you deleted pictures by mistake that you didn’t sync yet with your computer, can those pictures be recovered? The answer is a clear “it depends”.
As the iPhone (and consequently the iPod Touch and now also the new iPad) are part of Apple’s closed ecosystem, you as the user don’t have full access to the file system and - more importantly - cannot read or write directly to the flash memory where all your information is stored. In addition, any app on your iPhone is “sandboxed” and doesn’t have full access to the file system, let alone direct flash memory access, and thus cannot check for your deleted data, which is why there cannot be a tool like Data Rescue (which we offer for the Mac or PC) on the iPhone.
What happens when you delete information on your iPhone (similar to a regular hard drive), the entry in the file system is removed and the part on the flash memory that holds the actual information is added to the pool of free space, ready to be overwritten again by any kind of data. So even normal use, for example if you browse the web on your iPhone with Safari, the temporary files that get generated could already irrevocably overwrite the data you would like to get back.
Does that mean no data recovery is possible on iPhones? If you have the iPhone 3GS with the latest software installed, sadly, there is currently no known way to recover that data. If you’re using an older iPhone or haven’t updated your 3GS to the latest software, it may be possible to perform a function called “jailbreaking”, which would allow us to install certain software that in turn gives us direct access to the flash memory, and thus potentially recover the data you are after.
Realistically, however, the chances of actually finding your deleted data is fairly slim, especially if your device is more or less full with your data (music, videos, photos), as the chances of your lost data not being overwritten through normal operation tend to become zero quite quickly.
As a rule of thumb (just like for any other data loss scenario): if you have deleted data on your iDevice that had not been backed up, stop using it immediately and give us a call, so we can assess the situation and review your options.