Need to replace corrupted dll file in System32

Hi,

Win 7 x64

I want to backup everything for a move to Win 10. My backup fails and a restore point also fails. I tried using sfc and was told d3d10level9.dll was corrupt, and the store version was also corrupt. I have the original Win 7 media and a valid but old backup that I can extract the file from, but I cannot copy to System32 due to Access not valid. I copied the file to a new directory I made within System32 but still no access. I used copy and xcopy to no avail. From my research this is a very common problem in copying files into System32, but I haven't seen any solutions that work.

Futher investigation suggests using System Update Readiness tool and/or DISM; however both say to backup the PC before attempting either of those options. So if I can't backup I don't want to attempt this in case of disaster, so what do I do? I've heard of update in place but not sure what that does and you should probably do a backup before that too.

Arrrrggghhhh!

Norm