The correct chronological order of the events is as followed:
The Shah developed Western Policies.
Citizens of Iran protested the Government.
Ayatollah Khomeini came to power.
Traditional laws were reinstated.
Explanation:
Since the Shah of Iran was a close associate of West, he admired the culture of the west. So his significant policies were motivated by the West. He once even asked King of Saudi to Westernize Saudi Arabia, that's how much he loved the culture of the west.
Demonstration against the Government started in October 1977, because the policies were in favor of the West more than it's own citizens. Hence, working-class began protesting, there was also the issue of high unemployment, and the only work Irani's had was of laboring in the companies of the West. Further, the clerics were ignited by Shah's tactics of playing dirty campaign against the Grand Ayatollah Khomeini.
Looking at the mess when Shah realized that the protest is out of control he left Iran on 16th Jan 1979 and in the meantime, the Great Ayatollah arrived Iran on 1st Feb 1979 and took the power.
Right after forming the Islamic Republic of Iran,Ayatollah retained old civil laws and imposed more sharia laws.
