Half of my model dissapeared?

I am working on a gun model that is two meshes due to mesh triangle limit in the program I use. While editing “cube001” I think I pressed 3 on the top row and “cube” dissapeared. It still showed up in the explorer, but I could not see it. Alt+h did nothing, and control z brought it back, but also undid all my progress on “cube001” that I did today.

I was fortunately able to resolve it by going back to a previous save (I make a new file every time I save), and copying “cube” back into the project, so I ended up loosing nothing. (I also make sure that when working with multi part objects the “center” is always at 0,0,0). However I would still like to know what I ended up doing, and how to undo it.
Thanks in advance for any answers.

were you using the numpad at all? You might have hit /, which hides/unhides everything but the selected object.

The numbers on the top row control layer visibility. Possibly you shut off it’s layer?

No, it was a miss hit while trying to hit e, so its one of the keys around that. Also if I hid everything I would f been albe to get it back with alt h

You simply switched layers. The numbers at the top of the keyboard are assigned to layer numbers. If you hit ‘3’ then you switched to layer 3. All of your objects will likely have been on another layer (most likely layer 1).

Could you have hit “H”? If so hit [alt+h] to unhide all.

The problem was with layers,

The problem was with layers,