Recently, Microsoft pushed the "Creators Update" out to Windows 10. It was available in April but it seems to have been force-pushed in the past 2 days. On my mother-in-law's computer, Creator's caused Excel to render a "Bad Image" message when attempting to start declaring "MSVCP140.dll is either not designed to run on Windows or it contains an error". I attempted the SFC and DISM repairs as advised on Tom's site to no avail. When I attempted an Office repair, Office disappeared completely. At this point, I definitely started to panic.
Fortunately, I noticed a pending reboot due to an install/update. Allowing Windows to install that update and rebooting twice brought Excel and Office back to life. I did have to re-register the software but all is well now. If you encounter this issue, stop what you're doing and install/restart Windows. Anecdotally, I've since hear of many folks encountering similar issues.