How to play a MC in Reverse

I was creating an interface and I´m programming it, i’m trying to make a MovieClip play backwards.

The .fla works this way:

In the principal Timeline I have a MC called contents_mc, it contains the elements of the animation and the next & return buttons.

So, Frame 1 is the 1st screen, when you Release next_mc button, it has to play frame 2 to 25 (Frame 25 is 2nd screen) and when you Release next_mc button it has to play frame 26 to 51 (Frame 51 is the 3rd screen), I used the basic commands, you know, gotoAndPlay, stop, etc. and it works very fine.

The thing here is that I need to program the “return_mc” button so I can move from frame 25 to 1 (I mean from screen 2 to 1) playing in reverse frames and then if I´m on screen 3, move to screen 2.

The idea is to make this system work no mattering if i have 15 screens or 2. Any Ideas?

Also I’ve atacched my fla file, I’m Working on Flash CS4 and ActionScript 2.0

I’ve deleted all the stuff in the fla, so I only left a 3 color line to notice the changes from a screen to another

I’ll Love some help.

Thanx so much to everyone