Is Keynesian economics dead?

Is Keynesian economics dead? Keynesian economics which work very well from the end of World War Two to the 1970's when stagflation kick in, but in 1980's President Reagan did the other side of the coin of Keynesian economics, tax cuts and FED in late 1970's into the early eighties under Paul Volker raised interest over 20 percent and it all seemed to work until the financial meltdown of 2008. Now the fed has interest rates (the Fed Funds which are loans bank made to one another overnight are near zero) and it doesn't seem to be working.