Keyboard shortcut presets

The U key has no shorcut assigned. I think I removed it by mistake at some point. 

Is there a way to ID the default shortcut on a key whose shortcut got reassinged by mistake?

Also, can I save my keyboard shortcuts as a preset? I can't find a Save as optiong, just "undo" and "clear" Seems like there aught be a Save as option, to create a preset. Then I coould open the defailt settings for reference. As it is I have have a modified version of my keyboard and no, apparent, way to save it as a preset; so I can open the default for reference.

The only opeion appears to be "Eneter" which just saves the current custom version as default.