When you don’t know what to do, do something! Something could be to draw an auxiliary figure or write down all the information from the text one more time.
You need to process the information in order to create an auxiliary figure. This is one of the reasons this is a good idea if you’re stuck. The figure becomes a new way of dealing with the information and will hopefully get you started.
Another way to start with something is to rewrite the information using your own words, instead of directly copying the text. When you simply copy the text, you rob yourself from the opportunity to properly process the information. By writing it in your own words, your brain begins to think about the problem you have to solve.