CTRL + M + O will collapse all.
CTRL + M + L will expand all. (in VS 2013 – Toggle All outlining)
CTRL + M + P will expand all and disable outlining.
CTRL + M + M will collapse/expand the current section.
CTRL + M + A will collapse all even in Html files.
These controls are also in the context menu under Outlining.
Right click in editor -> Outlining to find these controls.
(After disabling outlining, use same steps to enable outlining.)
For outlining options: Go to Tools -> Options -> Text Editor -> C# -> Advanced -> Outlining for outlining options.