Microphone won't work

[Chewy]

what should the resistance be?

[ed klein]

The ohlms value (resistance) would depend on the voltage applied to the circuit, and the current draw within the circuit. This applies to both direct current (DC) and alternating current (AC) circuits.

But, for a simple two wire microphone circuit we would only need to test for continuity, or complete circuit without any open circuits.

Most electronic test meters will make a buzz sound when the circuit is complete, and no sound at all if the circuit is not complete or open.