The lost notebook of Indian mathematician Srinivasa Ramanujan, containing groundbreaking mathematical formulas, was rediscovered by George Andrews in 1976 in the effects of G. N. Watson. This “notebook” is made up of loose sheets of paper with over 600 formulas, some of which have been proven by Andrews and Bruce C. Berndt in their publications. Discovered after Ramanujan’s death in 1920, the notebook contains mostly q-series and mock theta functions which have applications in black hole entropy calculations. The unexpected discovery of this notebook has been compared to finding Beethoven’s tenth symphony, causing a major stir in the mathematical world.
https://en.wikipedia.org/wiki/Ramanujan%27s_lost_notebook