Angels have the Phone Box
When W10 gets into a problem and can't boot, after 3 tries it will take you to the Advanced Menu with options for resetting/repairing, etc. Did it never get to that point? or, did you not let it try to boot more than three times?
What is not working? It won't boot from the W7 disk? It won't read the disk as a W7 OS?
Perhaps you should grab the TechBench ISO and just do a clean install at this point. If you have your W7 key, you can enter it during installation, or any time later to activate the OS. (See my post #2). Also, a little more detail in your system specs (in your profile) would be helpful.