I replaced the head gasket on my ka24e motor and now it wont run .

Sounds like you don't have a good seal there. You are losing compression from the sound of it. Either the gasket is wrong, it required additional sealer with the gasket or more then likely you over or under tightened the bolts on reassembly. The bolt require particular torque requirements and if over/under tightened it will effect the seal and result in what you are speaking of.