• Digitize all human knowledge and as much art/literature as you can gather (books, music, movies, shows, games, even porn and random YouTube videos and discussions on online forums :) Most of that work has already been done.
• Store it on the most resilient (and simple/repairable) storage media you can,
• Bundle it with devices that can read that data,
• Along with instructions for building/reinventing such devices, and instructions on how to interpret that data (i.e. JPEG and other file formats :)
• Also include a guide for translating the instructions. Assume that a future reader may not understand any of our current languages, or even be human at all.
• Put it all in a silo as physically strong as you can build.
• Make copies of the silo and bury one on each continent and in each ocean. Maybe even on the Moon?
• Distribute markers and maps to each silo (and instructions for opening them) all over the world.
• Let fate take its course.
All of this could be done by a few individuals and most of it won't even require a lot of money.