stop()

btn2.addEventListener(MouseEvent.CLICK, backward);
btn1.addEventListener(MouseEvent.CLICK, forward);

function forward(event:MouseEvent) {
    if (this.currentFrame == this.totalFrames) {
        gotoAndStop(1);
    }
    else {
        nextFrame();
    }
}


function backward(event:MouseEvent) {
    if (this.currentFrame == 1) {
        gotoAndStop(this.totalFrames);
    }
    else
    {
        prevFrame();
    }
}