What do you want on your system Win7 or Win10?

Do you have any personal data on that drive that is not backed up?

If you have other purchased software, do you have the disc(s) and key(s)?

If your personal data is backed up, then a Clean install other either Win7 or Win10 is advised.

Clean means clean, no other drives connected, only mouse and Keyboard devices attached.
All data is erased from the install drive - Windows install will create the partitions it needs.

If you did not previously back up your personal data, you can use any number of ways to copy the data to an external drive.

Safe mode and
Xcopy source destination /E /V /C /I /H /K /X /B

XCOPY /? said:
source : Specifies the file(s) to copy.
destination : Specifies the location and/or name of new files.
/E : Copies directories and subdirectories, including empty ones.
/V : Verifies the size of each new file.
/C : Continues copying even if errors occur.
/I : If destination does not exist and copying more than one file, assumes that destination must be a directory.
/H : Copies hidden and system files also.
/K : Copies attributes. Normal Xcopy will reset read-only attributes.
/X : Copies file audit settings (implies /O Copies file ownership and ACL information.).
/B : Copies the Symbolic Link itself versus the target of the link.