Appoligies I got this wrong in my head, for some reason I thought that reverse was on a different plane to the other gears that you could select.
Of course if you can select multiple gears then it suggests the cables are not broken, however like Brendan pointed out the throw is out for selecting the forward position gears. The cables are set by fiat in the factory and althought there is some room for adjustment its not easy, and if the bottom gears are selectable you have to be careful not to adjust it too far the other way.
It could be the cable hasn't snapped but has stretched, when you push the stick forwards it pulls on the cable and pulls on the gear box selector so this is probably the issue.
Cables are easy to change, expensive to buy new. You could get one from a scrappy but remember you'll need access to the bottom of the car, which isn't always easy if the car is sat on its belly in mud.