What were the major factors or causes that ended the cold war? can they be attributed to a single person or a single event?

There were several factors that contributed to the end of the Cold War. This cannot be narrowed down to a single person or event, rather a series of them that happened gradually. Here is a comprehensive list:

1) Fall of the Berlin Wall - This wall that split East and West Berlin was a symbol of the differences between the United States and Soviet Union. When this wall was torn down by the citizens of East Berlin, it symbolized their refusal to live by the standards established by the Soviet Union.

2) Gorbachev's policies of Glasnost and Perestroika - These two policies allowed for more individual economic freedom (aka people could decide what they wanted to buy instead of having the government plan it for them). These policies also allowed for less restrictions on freedom of speech and media.

3) Soviet satellite nations demanding independence - Countries like Poland and East Germany demanded their independence from the Soviet Union during the late 1980's and early 1990's.