Short answers, pulled from the story.
Muhammad Shah ascended the throne in 1719 under the strict supervision of the Sayyid Brothers of Barha. He was only eighteen years old when he took power to replace previous rulers who could not maintain order.
Syed Hussain Ali Khan Barha fell dead that day after a group of assassins struck his encampment at Todabhim. The commander and chief of the Mughal army died during this attack which allowed Muhammad Shah to take direct command of the army.
Nader Shah attacked northern Afghanistan and captured Ghazni before crossing the Khyber Pass to besiege Peshawar by November 1738. He entered Delhi in February 1739 where he ordered a massacre leaving at least 30,000 dead after rumors spread about his assassination.
Urdu became more popular among people and Muhammad Shah declared it as the court language replacing Persian. Religious institutions for education such as Maktabs appeared during his reign while the Quran was translated for the first time into simple Persian and Urdu.
Jai Singh II of Amber completed the significant scientific work known as Zij-i Muhammad Shahi between 1727 and 1735. The document consisted of 400 pages dedicated to astronomical calculations and represented a major achievement during the reign despite administrative neglect elsewhere.
Muhammad Shah died due to grief on the 26th of April 1748 after hearing news about the Battle of Manupur victory. He became sick and did not come out of apartments for three days while fasting before passing away from emotional distress.