I did not back up my files in Windows 7 before installing Windows 8 on top of it, and it appears as though they are all lost.
Is my data recoverable?
Unless you had performed a backup, in which case it does not appear so, you would not be able to restore your Windows 7 installation.
Your best bet is to copy off any files/documents that you had prior to the upgrade and start fresh with a new Windows 7 installation.
Instead of downgrading, what issues are you experiencing that makes you want to revert back to Windows 7? Maybe this community has some solution to your OS woes.
Check if you have a Windows.old folder on your system partition:
The Win8 Upgrade should have created it, and unless you specifically got rid of it it should still be there. Keep your fingers crossed and search inside it for your files.
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