I recently upgraded a dual partition hard drive with the same image of Win 7 Pro to Win 10 and now have lost ability to use the Win 7 in a dual boot configuration.   All program files were loaded to windows.old even though I was only upgrading the current version of Win 7 that was operating.   I have the Win 7 OS and show a genuine version but none of the user accounts are present, and there is no admin account to make changes.   Can I reload the Win 7 from a install disc without impacting the Win10 partition.  All my recovery files are also missing.  Not sure if I did something wrong or if Win 10 just took over the drive.  I can still dual boot with no problem but the Win 7 OS is severely compromised and can only access this partition through a Win 10 admin account.

Hi LibbyTech, 

Thank you for your question. 

By my understanding, you could reload Windows 7 without any problems, it didnt affect Windows 10 partition. Windows 10 take over the driver and didnt move your recovery file, we suggest you check recovery file by Windows PE. 

If there are any questions regarding this issue, please be free to let me know. 

Best Regard, 

Jim