Faces becoming transparent / missing

[SketchBug]

I've been trying to make this hat for a minecraft character. All I've been using was cubes, not separate planes. But then, half of the faces started not appearing. I keep trying to add textures to them, but nothing works. When I try to replace these missing faces with single planes, it just looks glitchy. The only side that does seem to appear are the planes on the right and front, but the left, bottom and top tend to go missing. How do I fix this?

Side where the planes sort of appear:
https://gyazo.com/177fc78e6eb7d2f1cc22c9096d3db239

Side where everything is derpy:
https://gyazo.com/1aefe9aaba6c01366aa68994320b84b0

[JTK222]

You can click on that Cube with the Gear in the Element Edit Mode.
It will open a Menu where you can disable and enable single faces. Just select an element and you will see when it's disabled.
(There should be a blue "button" on the left site when they are enabled and a white when they are disabled.

[Sphax]

I think your faces are not hidden but the UV is probably wrong because elements are outside middle zone. Be sure to check UV of the "invisible" faces in element settings.

[SketchBug]

Thank you I manged to fix it it seems to work whenever I set my uv to "full" the moment I create a new cube.