2004 ford crown victoria police interceptor door locks will unlock but not lock how can i fix it?

SOURCE: 2003 Crown Victoria Police Interceptor

Assuming you have played with the child locks on the doors you may fnid that your particular car is missing the linkage from the interior door handle to the door lock. Apart from making up a rig yourself I would suggest going to a breakers yard or possibly your local Ford dealer

SOURCE: 2004 and 2001, are parts interchangeable?

Yes they are as long as the Motors are Similar.

SOURCE: 2006 ford crown victoria police interceptor power

You need to replace the switch which is not to expensive