Troubleshooting a Dell Docking Station
1. unplug the round, circular plug from the back of your dock. If you're having trouble finding it, it is plugged into the opposite side of the power button and should be connected to a wall outlet for power.
2. Once it is unplugged, hold down the power button on the dock for 5 seconds.
3. Plug it back in and with your laptop open and turned on, plug in the laptop to the dock and see if it connects.