ArcPy can't find numpy module

[MKF62]

I'm encountering a really weird error and I'm not sure what to do about it. I can't recall if I ran my script in 10.6 yet, so this could be a 10.6 problem as I recently upgraded from 10.5.1. 

I have a custom script tool in an ArcToolbox. I can run this python script in PyCharm IDE and it works great. When I try to run it from ArcMap, it tries to import the numpy module but fails as it can't seem to find it. While I don't use numpy in my script tool, I understand that the arcpy __init__.py script is where it is being imported. When I look in PyCharm, the Python interpreter shows numpy version 1.9.3 as part of the modules available, so I know it's there (and it's obviously there since the script works fine in PyCharm).

Error:

Python exe:

[MKF62 · Accepted solution]

Still not sure what exactly went wrong, but it must have been a corrupt install somehow. I used Control Panel > Uninstall Program > ArcGIS 10.6 > Uninstall/Change > Repair and it must have found the missing library because it works now.