|First, check to see if the pump and tubing are connected. They sometimes become disconnected when installing or cleaning. If the connection is loose, wrap some electrician’s tape around the pump’s outflow “nipple” so that the tubing and nipple form a tight connection.
Second, check to make sure there is not a kink in the tubing. This is an often missed problem, especially if a fountain was difficult to install.
Try tapping the pump on a hard surface to see if the impeller is stuck. Sometimes an impeller gets stuck in shipping. Tapping it might loosen the impeller enough to get it to spin again.
There might be air in the line between pump and fountain. Unplug the pump and plug it back in a couple of times to remove air bubbles.
If 1-3 above are not the problem, then your pump might be dirty. Remove the impeller according to manufacturer’s instructions, clean, and replace. Generally, you will need to snap off a cover to find the impeller inside. Usually, the impeller looks like a propeller.