Did you forget to enable RDP to only discover your mistake after you were remote to the machine?  Me too.  If you can get on the network, you can launch the registry editor and then point it to the remote workstation.  Change the following:

HKLM\SYSTEM\CurrentControlSet\Control\Terminal Server\fDenyTSConnections

Set the value from one to zero.

Really not much to add other than I sometimes feel the need to remove the Windows Firewall from the equation when trying to troubleshoot a problem.

Launch a command prompt as the admin (right click, select run as administrator) and enter the following:

netsh advfirewall set AllProfiles state off

I work remotely through RDP more times than not and every once in a while, the bar at the top of the RDP session becomes unpinned.  It bugs me and no matter what I do, all of my connections moving forward open with the session unpinned. 

Here's where you can fix this issue:

HKEY_CURRENT_USER\Software\Microsoft\Terminal server Client
"PinConnectionBar"=dword:00000001

As shown above, the value should be changed from zero to one.