1) Sayyiduna ‘Abdullah Ibn ‘Abbas (radiyallahu ‘anhuma) reports that when Nabi (sallallahu ‘alayhi wa sallam) was distressed he would recite:
‘La ilaha illalahul ‘Azimul Halim, la ilaha illallahu Rabbul ‘arshil ‘azim, la ilaha illallahu Rabbus samawati wa Rabbul ardi wa Rabbul ‘arshil karim’
لَا إِلَهَ إِلَّا اللَّهُ الْعَظِيمُ الْحَلِيمُ لَا إِلَهَ إِلَّا اللَّهُ رَبُّ الْعَرْشِ الْعَظِيمِ لَا إِلَهَ إِلَّا اللَّهُ رَبُّ السَّمَوَاتِ وَرَبُّ الْأَرْضِ وَرَبُّ الْعَرْشِ الْكَرِيمِ
(Sahih Bukhari, Hadith: 6346 and Sahih Muslim, Hadith: 2730)
2) Sayyiduna Abu Hurayrah (radiyallahu ‘anhu) reports: “Whenever Nabi (sallallahu ‘alayhi wa sallam) was worried about something, he would lift his head to the sky and say ‘Subhanallahil ‘Azim’.”
(Sunan Tirmidhi, Hadith: 3436 with a sound –hasan– chain)
3) Sayyiduna Abu Bakrah (radiyallahu ‘anhu) reports that Nabi (sallallahu ‘alayhi wa sallam) said:
“The du’a of a distressed person is ‘Allahumma rahmataka arju fa la takilni ila nafsi tarfata ‘ayn wa aslih li sha’ ni kullah la ilaha illa Ant’
اللَّهُمَّ رَحْمَتَكَ أَرْجُو فَلَا تَكِلْنِي إِلَى نَفْسِي طَرْفَةَ عَيْنٍ و أَصْلِحْ لِي شَأْنِي كُلَّهُ لَا إِلَهَ إِلَّا أَنْتَ
(Sunan Abi Dawud, Hadith: 5049. Declared authentic by Hafiz Ibn Hibban-rahimahullah-; Al Ihsan, Hadith: 970)
There are numerous other du’as one may read for financial difficulties etc. For more, kindly refer to Al Adhkar of Imam Nawawi (rahimahullah) and other such books.
And Allah Ta’ala Knows best.