When you say twisting the throttle had no effect, to what extent do you mean that? Did the motor sputter and chug but refused to spin up as you twisted the throttle? Or was there absolutely no change or effect whatsoever when you twisted the grip?
If the motor responded, but only sluggishly, I'd say the place to start is cleaning your carbs. Get your hands on a service manual for your bike and follow the instructions.
If there was absolutely no response at all, but the grip did indeed twist, then the problem's gotta be the throttle linkage. It's either just disconnected, which would be odd but not a big deal, or it's damaged or corroded in some way. Either way, it's no longer connected to your throttle bodies. Again, a manual is the place to start, which will walk you through identifying the throttle cable and checking that it's properly connected.
Let us know how it goes, and welcome to TMW!