After changing crankshaft sensor will not start

Was it running before the swap or was the swap an attempt to get it to start?
What testing was done that pointed at the crank sensor?
Do you hear the fuel pump run for two seconds when you turn the key on?

If you got a crankshaft position sensor trouble code, that does not always mean the crankshaft position sensor is bad, the error code only refers to that crankshaft position sensor circuit, it could be the wire, a loose connection, etc.
You need to post the code you are getting and then we can probably provide you with a trouble shooting chart for testing them sensor circuits.

Then why did you change it?
Do you still have the old one?
Do you have any codes now or even before?
Recheck the connection.

Like I said before, "If you got a crankshaft position sensor trouble code, that does not always mean the crankshaft position sensor is bad, the error code only refers to that crankshaft position sensor circuit, it could be the wire, a loose connection, etc. "

If it was running before the swap but not now and switching back to the old one did not do the trick you will need to start by checking the wiring to the sensor and the connector itself.