One thing I noticed is that people go into their C Drive properties menu or their folder's properties menu, and notice that the sharing tab is missing. Somehow, the sharing tab has disappeared. The sharing tab is just gone. This happened to me. I had opened my C Drive Properties, and noticed I had no sharing tab. It took me awhile to figure out the solution.
SOLUTION: Security Accounts Manager service must be started, and set to 'Automatic'.
Open Control Panel>Administrative Tools>Services.
Find 'Security Accounts Manager' on the list.
R-Click it, and open the Properties meny.
From there, you can set 'Startup type' to 'Automatic'.
Once it is started, your Sharing tab will be back.