'A' key stopped working

I am working on an object.
I go into edit mode.
I hit the ‘a’ key to select all vertices, but nothing happens.

I can select vertices using border select.
I can un-select vertices using MMB.
But the ‘a’ key will not select or un-select all.

I don’t have this problem in other projects.

Is there some way to disable the a shortcut key? Maybe I did it by accident.

Thank you everyone.

I think it’s very unlikely that you accidentally changed this shortcut (could be done in the User Preferences). I guess it’s a bug. Sometimes it happens in my projects that the y key and the z key are interchanged and I haven’t got an explanation for this behaviour either…

You say that the a key works in other projects. What I would do (maybe there’re better ways) is to open a new project and to append your scene…

Go to the Select menu in the 3dview header, and see if the shortcut is still behind ‘select/deselect all’. If not, right-click on it & ‘change shortcut’ or ‘add shortcut’.

Even when other functions have ‘A’ assigned to them, I don’t think they can override the default one