Prayer and fasting of a prisoner who does not know anything about time

If a person cannot find water, is it better for him to delay his prayer or to pray at the beginning of the time?

When Is Nafl Prayer Not Allowed?

Her menses started after the time for Zuhr began; should she make it up when her period is over?

The times of the prayers are close together in the North – is it permissible to put them together?

The people in his mosque pray Fajr before the proper time; should he pray with them?

Difference in the timing of Fajr and Maghrib prayers in Bahrain and Dammam

How can he catch up with the time of prayer?

How can he know the times of prayer when he is on board the plane?

Should he wake his family for Fajr prayer even though they are exhausted and tired?