The great recession ended when the government was able to enact fiscal stimulus programs. Most of them used a combination of government spending and tax cuts. This helped people to get back on their feet and be able to contribute to the growth of the economy.
Specific acts included the Economic Stimulus Act of 2008 and the American Recovery and Reinvestment Act of 2009. Even though the recession technically ended in 2009, the economic hardship lasted for a long time afterward.