Windows 10 can't find "C" on my computor

What can I do, I spent about 7 hours on it this early a.m and tried to figure out something. All I got was could not find "C" and Admin securitys . Also looked liked, unknown network names. I did do some Diagnosie , and I think I sent the feedback to Microsoft. It was so hard to get any help from Dell or Microsoft because my Warrinty     is out of date. Sorry for this long post, but I'm so fedup. Some of my App won't open up can't find "C" it says ???