In my position I could sacrifice Buried Treasure to get one mana and then with my 4 lands and this mana I could have paid for its ability from the graveyard. But the game considered that with a land in hand, no active ability in the battleground and my 4 lands I no longer had any possible action and automatically ended all my main phases. I didn't even have the opportunity to sacrifice Buried Treasure except during the combat phase, but if I did it then, I would have lost the mana once I left the combat phase and I wouldn't have been able to pay the 5 mana during my second main phase for its ability from the graveyard.