A. 1. Check for updates: Make sure you are running the latest version of the game, as updates often fix bugs related to level progression. 2. Complete all objectives: Ensure you have completed all tasks and objectives in the previous levels, as some levels may require specific achievements to unlock. 3. Restart the game: Close the app completely and restart it to see if the levels unlock after a fresh start.

B. 4. Clear app data: Go to Settings > Apps > Terra Nil > Storage > Clear Data. Note that this will reset your progress, so use this as a last resort.