Hi Jaber, I am Paulo. I'm an Independent Advisor and an individual like you inclined to help.
First, I'd give it multiple restarts and see if that will remount the internal drive. If not, since it acts like an ejectable drive, you may use the method in the link below to remount it
https://www.thewindowsclub.com/remount-ejected-...
(Standard disclaimer: This is a non-Microsoft website. The page appears to be providing accurate, safe information. Watch out for ads on the site that may advertise products frequently classified as a PUP (Potentially Unwanted Products). Thoroughly research any product advertised on the site before you decide to download and install it.)
I hope this helps