Sayyiduna Ubadah bin Samit (Radiyallahu Anhu) reports that the Prophet of Allah (Sallallahu Alaihi Wasallam) said: "Whoever's sleep is broken in the night and he recites the following Du'a and thereafter asks Allah (SWT) to forgive him or he makes Du'a, Allah will forgive him and accept his Du'a. And if he makes Wudhu and performs Salah, Allah will accept his Salah."
The Dua is:
*لاَ إِلَهَ إِلَّا اللَّهُ وَحْدَهُ لاَ شَرِيكَ لَهُ، لَهُ المُلْكُ وَلَهُ الحَمْدُ، وَهُوَ عَلَى كُلِّ شَيْءٍ قَدِيرٌ، اَلْحَمْدُ لِلَّهِ، وَسُبْحَانَ اللَّهِ، وَلَا إِلَهَ إِلَّا اللَّهُ، وَاللَّهُ أَكْبَرُ، وَلاَ حَوْلَ وَلاَ قُوَّةَ إِلَّا بِاللَّهِ
Transliteration: Laa Ilaaha Illallaahu Wahdahu La Shareeka Lahu Lahul Mulku Wa Lahul Hamdu Wa Huwa Alaa Kulli Shay'in Qadeer, Alhamdulillah, Wa Subhanallah, Wa Laa Ilaaha Illallaahu Wallaahu Akbar, Wa Laa Hawla Wa Laa Quwwata Illaa Billah
Translation: There is no god besides Allah, the One, He has no partner and to Him alone belongs all kingdom and praise and He is able over everything. All praise is due to Allah, glory be to Allah and there is no god besides Allah and Allah is the greatest, and there is no might and power except by Allah.
(Sahih al-Bukhari, Hadith#: 1154)