First off, don't connect it to iTunes. If you connect your iPhone to iTunes and let it sync, it may well take a new backup and overwrite your old one. If your old backup gets overwritten, the iPhone Backup Extractor probably won't be able to find your data.
If you need to connect your iPhone to iTunes for any reason, take a backup of the backup folder first (see the paths below), as you can restore from this copy. The iPhone Backup Extractor can restore from backups on CD, DVD, network shares or other computers.
Finally, download the free iPhone Backup Extractor, run it, and see what data it can find. There's no need to have iTunes running or even installed.
Depending on the type of PC or Mac you use, iTunes will store your backups in one of a few possible locations.
- Under OS X, iTunes will store backups in /Users/USERNAME/Library/Application Support/MobileSync/Backup
- Under Windows XP, iTunes will store backups in \Documents and Settings\USERNAME\Application Data\Apple Computer\MobileSync\Backup
- Under Windows Vista and Windows 7, iTunes will store backups in \Users\USERNAME\AppData\Roaming\Apple Computer\MobileSync\Backup