FirkeyAegis

What car is that? Because when I am trying to pack all my bass guitars it is always not fitting in my car and when I am going for an event I am sending those guitars through FedEx

A guitar tech or luthier could possibly replace the nut if the rod itself is intact. If the truss rod is broken, though, replacing the neck might be your best option. You can look for a used Squier neck or an affordable aftermarket one like Mighty Mite. Try to avoid spending too much since it's a budget bass. In the meantime, if the action is playable, you could keep using it as-is until you find a solution.