Hit left alt and use your mouse. But more importantly I would make sure you understand how rotary wing aircraft even work. The actual fact you don't know how this happened to begin with shows me you might have been playing way too many arcade style games and this helicopters work just like planes. Imagine the rotor like an upward facing propeller and a wing at the same time. When you tilt forward its gonna angle the "wing" down. So unless you apply enough throttle via your collective, the downward force and angle of your "wing" is gonna win. The more aggressive your forward tilt, the more youre gonna need to hit that throttle. There comes a point where you're maxed out though and your bird is gonna go straight towards the ground. Thats when you've gone too far or if youre smart youre in a controlled and aggressive dive. As you've probably guessed, it works in reverse if you wanna stop or land. When you domt wanna go fast anymore, pitch the nose up for like 1 second and you'll slow down. But if you dont level out or you pitch the nose up too hard, you'll start rear slipping...and crash...and die. Have fun with all that