G-day mate!, It just started slipping out of second at first!

What is your question?

G-day yeah, it just started slipping out of second at first. Made an appointment and then on the way to get it fixed, suddenly there was no gears at all, just stayed in neutral. And the leavers, or the two cables that I could see seemed to be working alright right down to the gear box. So I think the problem is inside the gear box its self. And was just wondering if this same problem has happened to others. And was it expensive, or is there an inexpensive solution? Or could it be a variety of possibilities, however I didn't hear any crunching or snapping noises going on. But it just started slipping out and then almost as if something got wedged in the wrong place I think. But still I am no expert, so that's why I am sending this message hopping for some expert advice.