Go to Lowes/Home Depot/Lumber yard/the local forest and get some wood. Two trees should do it. Cut them with an Xacto knife, so they’re really straight. Then take a couple of nails (not the ones that grow on your fingers/toes) and see if there are any holes in the wood in which you can stick the nails. Bang the wood against your wall with a hammer. The louder, the better. If you share an apt, et al, and your neighbors complain, tell them to stop it or you’ll offer to make them a bookcase as well. Cover it in penguin flavored duct tape.
Once the bookcase falls down, make a bonfire with the wood and go to Ikea.
Hope I was able to help!