Flash How do you turn the flash off on the Nikon d70?

SOURCE: nikon D70 flash doenot fire

According to my information, the camera may need a new flash PCB (printed circuit board). Check the repair service search on this site for someone in your area. The part number for the circuit board is: 1S014-020-1 and runs about 50$

SOURCE: nikon d70 firmware version 2.0

From your question it isn't clear whether or not you are formatting the card in the camera.  Is this how you are formatting it?  If not, you should try doing just that.  
Do not use a computer to format the cards for your camera.  In the future, use only the camera's own formatting and do it after every time you transfer your images to your computer.  In case you don't know how to format the card with the camera, let me know and I will explain it.

SOURCE: I can't seem to turn the flash on my Nikon D70 on!

If nothing else it should pop up when you put the camera in A or M or S and then press the flash button on the side. It might or might not fire, depending on the light available, but it should for certain pop up. When you do this, you should hear a click and the flash should pop up. If you hear the click and it doesn't pop up, then it's jammed or glued or somehow being mechanically prevented from coming up.

In Auto modes, you can select the flash to off with the side button and the back rotary selector. This is where the flash symbol with the slash through it tells you the flash is off. If you push the flash button in Auto modes with the flash selected off, it won't pop up.

There are also some things the D70 can do to control external flash units that may be set abnormally.

The best way to make sure those aren't messing you up is to select "reset to default". That will take the camera back to a base setup that should work.

If none of these things gets it going, take it in to the Nikon dealer in town.