It is narrated from Sayyiduna Utbah bin Ghazwan (may Allah be pleased with him) that the Prophet of Allah (peace and blessings be upon him) said: "When one of you loses something, or wants help while he is in a land where there is no human being, let him say: O servants of Allah, help me! O servants of Allah, help me! For Allah has servants whom we do not see." And this has been tried and tested.
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 14362