My compressor is a single stage oil injected screw air compressor.
I have changed the oil filter ,oil separator, air filter and top up but oil and air pressure is not developed
I your compressor is not producing any air, there is probably something wrong with the load/unload (control system).
There’s an inlet valve on the intake side of the screw element that opens and closes according to air demand.
It is controlled by compressed air, which in turn is controlled by a solenoid valve, which in turn is controlled by the control panel and/or pressure switch.
Please check those one by one. Start at the pressure switch or control panel. If those are ok, check that the solenoid valve receives power and is actually switching.
If all those are ok, the problem is probably a stuck inlet valve. Be careful when opening those, they usually contain a big spring under tension.
Let me know if you need any more info or find out something more.