Somewhere along the line you changed your Default Workspace to something else. Most likely the Basic setting.
When this happened, you were given a dialog box alert that said that the setting would change your menus. But you probably didn't understand what that meant.
At that point you had fewer menu items because the Basic setting is meant to make it simple for people who don't know what they are doing to look through shorter menus.
But in your case it flummoxed you.
I don't blame you. This is one of the first things I now teach in trouble-shooting ID.
Just switch back to the Default Workspace and you'll be fine. And then don't mess around with the menus in the Edit menus dialog box.
Over the years Photoshop has shown a great delight in, about once ever month or two, resetting itself to factory defaults. Now I notice it has taken to hiding a lot of my menu items and I have to click 'Show all menu items' every time I open a menu. Most frustrating. And I can't find a way to force the blighter to do the decent thing and keep on showing me all the menu options. Can anyone tell me how to do this as the help files are less than forthcoming.