Okay I'm about to go crazy! I'm stuck on Nancy Drew Danger By Design and..

Go back to Marchand, you can buy it again for 8 euros.

Please note that I don't have the game, I just used Google to try to help you. Apologies if it doesn't work. Good luck!

If you're talking about the decoder thing, you don't need it. All you have to do is find the drink to get the decoder, then at some point, Dieter is at the park and drops a couple of things, and after you pick them up, go visit him, and he will tell you what they are. The clock thing fits into the wall, and a secret passageway opens up after you make all the clocks turn to 3. Go through the tunnel and open up the the slot thing where a book sits. All you need to do after that is look at the magazine in minette's room about her, and Nancy will comment on one of the pictures in the second page. If she didn't say anything, look around her room until you find three big rocks, then look back at the magazine. Nancy should say " this picture looks like it was cropped" or something like that, then you have to go and talk to Jean Michel and ask him for the version of the pic that isn't cropped, then after that, open up the decoder thing and click on the bottom of it and you should see three dials. If you look in nancy's journal where she keeps her notes, it should say something about where the three dials in the uncropped picture are set, and then you set the dials in the same positions as the rocks, and type the coded message in the book that you got from the passageway at dieter's. If I skipped something, or if you are still stuck, Go to youtube . Com and search:
Arglefumph nancy drew danger by design
And I think it will really help. It has helped me alot.