Format code shortcut for VS2010
Visual Studio WITH C# KEY BINDINGS
To answer the specific question, in C# you are likely to be using the C# keyboard mapping scheme, which will use these hotkeys by default:
Ctrl+E, Ctrl+D to format the entire document.
Ctrl+E, Ctrl+F to format the selection.
You can change these in Tools > Options > Environment -> Keyboard (either by selecting a different "keyboard mapping scheme", or...