Amals to find a lost item

Sayyiduna ‘Abdullah ibn ‘Umar (radiyallahu ‘anhuma) narrates the following dua from Rasulullah (sallallahu ‘alayhi wa sallam) to be recited for a misplaced item:

(المعجم الكبير للطبراني، الرقم: 13289)اللهُمَّ رَادَّ الضَّالَّةِ، وَهَادِيَ الضَّلَالَةِ تَهْدِي مِنَ الضَّلَالَةِ، ارْدُدْ عَلَيَّ ضَالَّتِي بِقُدْرَتِكِ وَسُلْطَانِكَ، فَإِنَّهَا مِنْ عَطَائِكَ وَفَضْلِكَ

O Allah! The Returner of the lost and Guide of those astray, You are the Being who will show the right way out of misguidance, return my lost property to me with Your power and command because it is from Your gift and favour. 

On one occasion Abdullah ibn ‘Umar (radiyallahu ‘anhuma) mentioned to make Wudhu, read 2 Rakaats of salaah and recite the above dua after the Tashahhud in Salaah. (مصنف ابن ابي شيبة، الرقم: 29720)

‘Allamah Ibn ‘Allan (rahimahullah) has cited another du’a which through experience of the pious has proven to be effective.

يَا جَامِعَ النَّاسِ لِيَوم لَّا رَيبَ فِيهِ إِنَّ اللهَ لَا يُخلِفُ المِيعَاد

or you could recite the following version:

يَا جَامِعَ النَّاسِ لِيَوم لَّا رَيبَ فِيهِ أَجمِع عَلَيَّ ضَالَّتِي

(Al Futuhatur Rabbaniyyah, vol. 5 pg. 151/152)

Oh the Gatherer of mankind on a Day in which there is no doubt, Certainly Allah does not break his promise. Return my lost item to me

Some have even found the recital of only the words: Ya Jami’u frequently to be effective in such cases.

Mufti Shafee’ Saheb has mentioned the following Amal:

As soon as one comes to know about the lost item recite إنا لله و إنا إليه راجعون eleven times. This Amal has been proven to be effective.

(Source: HadithAnswers.com with additions)