Turning on the ignition leads to a prolonged clicking sound, but the engine does not start.
This can be caused by either a low battery charge level, or a loose connection in the starter circuit. The battery needs to be fully-charged, and load-tested, to ensure it is not the issue. All starter wires need to be checked to ensure tightness. If a connection appears to be burnt or loose, the battery will need to be disconnected by removing the negative battery terminal, in order to tighten the connections. Other possibilities are the starter relay, and the starter itself, being an issue. You may want to enlist the help of a mechanic, such as one from YourMechanic, who will have the equipment and expertise to diagnose the starting system, and be able to repair the issue of the engine not turning over.