Sniff,
How do you know the battery is flat - does the starter solenoid click/do the instrument panel lights come on etc?
If 2nd gear no good for starting, try 3rd (!) - as long as she'll turn the wheel (i.e. so long as it doesn't lock up when trying to bump start) then she should force the engine to turn over...
Did you check the fuses etc?
Do you have a multimeter? What voltage are you getting across the battery?
Any other problems before this happened? How long was the bike 'ok' for before this etc - is there any other information/possible cause/anything that has been changed lately etc - is there actually fuel in the tank?! On reserve, carbs have fuel, engine has spark etc?
Get back with more info please?
Paul