I just ran into the same exact issue. Luckily, I managed to somehow fix it by heading into a special stage, and then force-closing the game (I was on PC). Continuing the game (which stated that I was in Special Stage 1) brought me to LRZ2 with my score and precious emeralds back. So if anyone else runs into this problem, try doing that. I would've lost all will to continue if I lost all of those emeralds.