Cropping page with layers

Hi
I've attached a file that I'm trying to crop. It's got about fifteen layers that need to be cropped to the same size and the mouse off page. Can someone help me do this please. I've tried moving the margins of the back page but it isn't reducing the layers.
Thanks robin

I took a look at your file but it's empty.

Attachment not opening , sorry, I'll try again

Once again the attachment doesn;t open. I'll try again sorry to mess you all about. :(