Emma Goldsmith wrote:
If you've already been using the shortcut, there's not reason for it not to work now, unless you've changed it without realising it.
Go to general options (File>Options>Keyboard shortcuts>Editor) and scroll down to "Confirm and move to next segment". This should be set to Control+Enter.
Other profiles (SDLX, Trados) have other shortcuts for this action (Enter and Alt+Add), so it's possible that you've switched to another profile.
Edited to add: In Studio 2011 the path to shortcuts is Tools>Options>Keyboard shortcuts>Editor. The path above was for Studio 2014.
[Edited at 2014-03-12 15:06 GMT]
I have come across cases in Studio 2014 in which "Confirm and move to next segment" does not save certain segments, and even segments with 100 % match (green symbol) in which such an (accidental) operation has "unconfirmed" such a segment. The result is that Studio never displays the file as 100% translated when finishing the project. I haven't checked yet if the segment(s) in question nevertheless is exported so that the lack of confirmation is just an error or not.