The way I understand his question, maybe this rewording is more accurate:
"...After installing Windows 7 from a usb stick, after allowing Windows to format the HD, what is the best way to recover data?"
For the benefit of newcomers to data recovery...
If the Windows 7 formatting was a full format, data recovery will be practically, pretty much, impossible.
If the Windows 7 formatting was a quick format, even though the folders structure and file pointers are probably long gone, it is possible to use free or pay-for data recovery utilities that search the affected HD for recoverable files. Files not overwritten might be recoverable. There are numerous end-user and software variables that affect the chances of success. I'm a beginner, so my test-recovery success has been so far checkered.