Pretty much it is buy a new switch.
There is nothing you can set or configure on a unmanges switch. All the ports should function the same.
So I guess it depends on what doesn't work. If for example nothing works on certain port but these same devices and cables work on other ports then the switch is likely bad. It could also be bad cables that will work on some ports but not others. If you can get the port working with any combination of devices and cable then it is not the switch.
They are very stupid devices they keep a table of what mac address is plugged into what port and forward traffic based on that. This is all done by hardware inside a single chip on smaller switches which is why a switch is do fast.