I guess I'm a bit confused... You know your A/C system had a slight leak and now the freon has leaked out and the system no longer works... And that is strange? Did you expect that it would continue to operate forever? What happend seems pretty normal to me.

On most A/C systems there is a pressure switch in the system that will prevent the compressor from engaging if there is insufficent freon in the system for proper operation. If this switch is working on your system (and you indeed don't have freon) you will not be able to turn on the A/C system.