It needs three things to run.
Fuel, air and an ignition source.
Start with the fuel flow from tank to carburetor.
Check the choke. Is it open all the way?
Remove the spark plug, lay it against the cylinder head fins and push the bike forward at a good pace, clutch engaged, plug wire attached, while watching for spark at the plug's electrodes.
Confirm you have those three things then get back to us with what you find.
Tom