Does saying “Innahu ‘ala raj’ihi la qaadir (Verily, (Allaah) is Able to bring him back)” help to bring back something that has been lost?

This is not reported in the Book of Allaah or in the saheeh Sunnah of the Prophet (peace and blessings of Allaah be upon him). It is not one of the usual means of finding things that have been lost. It comes under the heading of using the Qur’aan for purposes other than that for which it was revealed. It also involves specifying a certain number, which is something that is a tawqeefi matter (i.e., it can only be known through revelation) and cannot be known through ijtihaad or reason. Using this method is bid’ah (reprehensible innovation), and it was reported that the Prophet (peace and blessings of Allaah be upon him) said: “Whoever innovates something in this matter of ours (i.e., Islam) that is not a part of it, will have it rejected.”(Narrated by al-Bukhaari and Muslim). 

And Allaah is the Source of strength. May Allaah bless our Prophet Muhammad and his family and companions, and grant them peace.