Windows 8.1 disable by default for the Administrative Share / root of each volume (c$)

Administrative shares have been disabled in Windows Vista and later versions of Windows for security reasons.

According to Microsoft Support Knowledge Base article 947232, you can do one of the following:

1. Create your own shares with the appropriate permissions (recommended);

2. Run the Microsoft Fix It to perform an automatic workaround; or

3. Add to the Registry subkey
   HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System
   a DWORD (32-bit) Value LocalAccountTokenFilterPolicy with the value of 1.

(source)

You should also verify the following settings in Control Panel / Network and Internet / Network and Sharing Center / Advanced sharing settings :

Network Discovery : On
File and printer sharing : On
File sharing for devices that use 40- or 56-bit encryption : Enable
Password protected sharing : Off