My pump isn't working
Check there is power to the pump itself.
If you can hear or feel the pump working but there is no water flowing first try switching on and off, there may be an air lock in the pump.
If this doesn't work disconnect the pump outlet - does it pump water once disconnected? If so reconnect and check all connections, check tubes are not kinked and pipes are not blocked.
If the pump does not work at all and is not making any noise or showing any sign of life it needs replacing.