Verify your ISO is specifically for Windows 7 Ultimate . You cannot use an Ultimate key on a different edition.
Download dedicated 64-bit drivers for your motherboard chipset, graphics card, and network adapters directly from the hardware manufacturer's legacy support pages. product key windows 7 ultimate 64 bit build 7600 install
If you can still boot into Windows, you can also create recovery disks from the manufacturer’s recovery software. Verify your ISO is specifically for Windows 7 Ultimate
Boot from a Windows 7 Ultimate 64-bit DVD or a bootable USB drive containing the ISO. product key windows 7 ultimate 64 bit build 7600 install