Lost my endless save

Today I was playing survival fog endless and I got a sprout so I was thinking I would go to zen garden and check what the new sprout is. But when I re-enter the endless level, my layout blinked for a second and then it disappeared. Everything went back to the very beginning. I already completed 158 flags and suddenly all went to nothing. I was even hoping getting to like 1000 flags? But now that seems impossible. Please fix this glitch or I dare not to play endless anymore.