It is hard situation when you know the server is on but cannot connect to it because Remote Desktop is not enabled.
There are two thing you can do:
1) If you are able to connect to server through Remote Registry, then navigate to
key, find fsDenyTSConnections value and change the it to 0
2) If the computer is domain joined then it is possible to create a group policy which disables Windows Firewall.
Computer Config > Administrative Templates > Network > Network connections > Windows Firewall > Domain Profile > Windows Firewall: Protect all network connections =
Then you will have to wait 60-90 for the group policy to apply and hopefully you will be able to connect afterwards.