Hi. I am making a small 2d platform game in Unity. 

Im having trouble imagining good puzzles and obstacles for the levels . I was wondering if there is a method to help me with this subject. Maybe a book or course that could help me. 

Its not about programming. Its about design and drawing ideas on paper.

Thanks

Try playing some puzzle games. I recommend Monument Valley for mobile phones, and the Professor Layton games for Nintendo handhelds. And Myst for PC, if you can find it. 

Or hire a game designer.l

DevMag ran a six-part series on "how puzzle games are designed" that may be of interest.

Thanks jbadams! I will read this articles and search for others.