with the engine off and the machine cooled down... and a flashlight or trouble light, try to see if the ground drive belt is still on both the engine pulley, the two clutch idler pulleys and the larger driven pulley toward the rear o top of the tranny ( this is a long belt, hidden way back up in the main frame channel - you may have to remove the mower deck to get a good look at it).
If it "looks" good, CAREFULLY start the engine, try to drive the tractor and see if the large driven tranny pulley is being turned.
If so, Then time to get professional help or take tractor to shop, imho. Above all, be safe - easy to get hurt up under there.

I have a craftsman Lawn Tracter number 917.273520 with a hydro-gear transaxle. I broke an axle and have replaced it. i have filled it up with 20-50w motor oil made sure the lever that disengages the transmission for pulling is engaged so it can tram. But the axles won't turn. I have the tires off so i can see if the axles turn or not, so it's not a axles pin. I do have the tractor rear wheels raised so i could pull the tansmission. i did not have to mess with the hydralic pump, so all that was still in place. But neither axle will turn.

what circumstance broke that axle? Ans did you have to crack the tranny case to replace the axle?
Other things to chk: make sure the driven pulley on the tranny is not slipping/spinning on it's input shaft.... also, make sure the park brake caliper assembly is not frozen up. Recheck your control linkage hookups. And did you purge the tranny of air after you drained/added fluid?

Broke a key that holds the axle from coming out and yes i did have to crack the tranny case to change the axle. Also the driven pulley on the shaft is not slipping. I will check on the park brake assembly to make sure it is not frozen up. How do you purge the tranny of air after you drain and add fluid?

craftsman usually puts purging instructions in their manuals. Did you read it?

YES, I SEE NOW HOW I CAN PURGE THE TRANNY, THANK YOU. DOES THE FLUID YOU PUT IN HAVE TO BE 20/50 SYNTHETIC OIL OR PLAIN 20/50 MOTOR OIL. AND EXACTLY HOW MUCH OIL IS REQUIRED?

if yours is a "serviceable" type tranny (designed/eqipped to allow user to change tranny fluid), then capacities s/b in owner's manual. If not, hope you captured/measured all the old oil so as to know how much fresh to put back in. Synthetic is usually the oil of choice.
Beyond that, can only suggest contact the tranny's mfgr's service dept for such info. My crystal ball has certain limitations.