Turn off your John Deere 1070 tractor.
Try to start the tractor. If the engine won't turn over, then the electrical problem could be with the battery.
Move the mower engagement lever to the "Park" position if it is in the "Engaged" position, then try starting the tractor again.
Lift up the front hood on the tractor and inspect the battery terminals to see whether they're corroded. Clean the terminals with a dry cloth.
Connect jumper cables or a battery charger to the battery terminals to charge the tractor battery. Turn the key to start the tractor again once the battery is charged.
Replace the battery, if the battery won't charge at all. You might have a dead cell in the battery -- you can buy a battery from a John Deere retailer.
Check the lights, if your engine is turning on, to see whether you have an electrical problem with a front headlight not coming on.
Open the front hood and remove the screws from the side panel that the broken light is on.
Connect the light plug at back of the bulb connector if it is disconnected. If the plug is connected, the unfasten the old bulb and replace it with a new one.