Du'a For One Afflicted By Calamity

To Allah we belong and unto Him is our return. O Allah, recompense me for my affliction and replace it for me with something better.

And We will surely test you with something of fear and hunger and a loss of wealth and lives and fruits, but give good tidings to the patient,
Who, when disaster strikes them, say, "Indeed we belong to Allah , and indeed to Him we will return."
Those are the ones upon whom are blessings from their Lord and mercy. And it is those who are the [rightly] guided.

[QS Al Baqarah :155-157]

Umm Salamah (RA) reported that Rasulullah(SAW) said: "Whenever an affliction strikes a muslim and he says, as Allah commanded him, "Inna lillahi wa inna ilayhi rajiun. Allahumma ajirni fi musibati, wa akhlif li khayran minha – To Allah we belong, and to Him will we return – O Allah, reward me for my affliction and replace it for me with that which is better," Allah will then surely replace it for him with that which is better."

Ameen Ya Rabbal Alameen