Ah yes, the strategy of replacing stuff without finding out the problem. Sounds like more profits for the local shops.
This could be as simple as the light blue wire having fallen off the solenoid S tab.
Before you get too far you may care to test what you have and find out what is working.
The best tool is a 12V test bulb and long leads. Costs about $5 but is soo easy to use.
Hook one end to the battery negative and go looking for voltage.
Youw ant to find a Bright bulb when you connect to a light blue wire and turn the key to Start. This wire goes to the solenoid S tab to start the engine.
If you do not have voltage here go back to the under column connector. There is a light blue wire coming out of it. Try here for voltage in Start. There is possibly a neutral safety switch somewhere in the harness just before this so it i simportant to check the light blue wire at several locations up to the switch before concluding it is a duff switch.
If you still do not find any check the Red wire going in to the connector, are you finding a Bright bulb here? If so then the switch and/or harness above the connector is not doing its job.
Here is a diagram which may give you afew clues about how the swicth itself operates. It is for a 1984 but very similair.