The reason for remote tab missing in computer properties would be that terminal services may not be running on your computer. You can check the status of this service in Service Management console which can be opened by running Services.msc from Run window.
If the service is not running, you need to put it back into running mode to restore the remote tab in My computer properties. If the start type of the service is set to manual then you can do this. But if the start type is set to Disable then you need to change the start type to Auto or Manual and then only you can start the service. So the only way you can start the service is by changing the start type to Auto and then rebooting the machine for the changes to take effect.