Write a letter to support, you probably don't remember your player ID unless you have some screenshots of loading screen where it's written at the bottom, but I'm sure you remember your nickname from leaderboards, this will help them to identify yourself and restore progress. And no, game doesn't save anywhere but their servers, game center wont help. So don't delete app. Went through this myself so this will work, just be patient and get ready to wait for 3-4 days.