At times of tribulation and hardship, you can say these supplications: • “Allahumma inna naj`aluka fi nuhoorihim wa na`udhu bika min shururihim.” • “La ilaha ill-Allah Al-`Athim Al-Halim, la ilaha ill-Allah Rabb Al-`Arsh Al-`Athim, la ilaha ill-Allah Rabb ul-samawati wa Rabb ul-ard wa Rabbul-`Arsh il-karim.” • “La ilaha illa anta subhanaka inni kuntu min ath-thalimin.” • “A’udhu bi kalimat-illah il-tammati min ghadabihi wa min sharri `ibadihi wa min hamazat ash-shayatini wa an yahdurun.’ • “Allahumma rahmataka arju fala takilni ila nafsi tarfat `ayn wa aslih li sha’ni kullahu la ilaha illa anta.”

there is no sound hadith or report which states how old the Mahdi will be when he appears.