Historically, Digital River has been used by Microsoft for its download services. Some users have reported success in downloading Windows 7 from here, but be cautious and ensure you have a valid key.
Websites like heidoc.net (Joachim Schmitz's Windows ISO Downloader) have reconstructed the database. You can use the Windows and Office ISO Download Tool (open source, safe) to fetch the exact 64-bit ISO for your edition.
: For business users who still have access to a corporate account, the VLSC may still provide licensed downloads for Windows 7 Pro or Enterprise.
(free, and works well for Windows 7) to create a bootable USB drive from the ISO file.
Choose the : Use MBR for older BIOS systems or GPT for newer UEFI systems.