If you have ever run into an issue where you have set up a server but forgot to put the tick in the box to enable remote desktop, then read on!
Many times I have done this and then had to go all the way over to the server (sometimes in different offices) to enable it.. if only I had known!
Just connect to the remote registry of the server in question and head to
Under the Terminal Server key, you'll find a REG_DWORD value named fDenyTSConnection. Double-click on that value to open the Edit DWORD Value box and change the value data from 1 (Remote Desktop disabled) to 0 (Remote Desktop enabled)