I got some wrong measures from a client. He wrote it should be 430mm x 340mm, but it was a mistake. It should be 590mm x 420mm. Can I change the document in the document settings without it will mess up the content on the document? I have taken a screenprint of it. You can see the image I have attached.
If you need to change the entire document, File > Document Setup.... is a better option, I think, but I would go to the Liquid Layout panel and enable Layout Adjustment from the panel flyout menu first to give yourself a leg up on adjusting the positing of any objects snapped to guides.
That said, there is no really clean and painless way to make this change.