changed alternator...wont crank!

Agree with 273. The alternator has nothing to with starting the car. If you have a fully charged battery, the car should turn over and run for several hours without the alternator connected. I assume you disconnected BATT- before removing the ALT, because if the ALT output wire touched ground, your battery could become a welder. First thing is see if your battery holds 12 V while trying to crank. Requires a multimeter ($6 or free).