Attempting any install or upgrade without first backing up files is reckless.
If the DVD Repair console finds an installation but can't repair it, click through to Startup Repair and attempt to run it repeatedly with reboots.
Next, download and burn to CD free Partition Wizard bootable manager, boot, select 1 for screen res, click on Windows 7 and see if you can explore files to know whether they still exist. If so, you can try copying the data to an external drive or another partition using Command Line, or install Windows 7 to another partition to browse from to copy your files over or onto external.
Or you can use Hiren's boot disk to boot to attempt to copy your data onto another partition, USB flash stick or external.
Once you get your files rescued, you can wipe the HD using Windows 7 DVD to do a clean formatted install, unless you have stashed your files in a partition on the HD, then use Partition Wizard to only wipe the other partiitions and leave the saved-date partition alone.