Backface culling. It's a rendering optimization. Most of the time you don't need to draw triangles that are "facing" away from the camera because they are obscured by other triangles.

http://answers.unity3d.com/questions/711/transparency-and-backface-culling

Just invert the faces and problem solved.

Good Luck

I assume from the way it's described that the room you made is one object. Because of this, only one side of this object can be lit. If you want to be able to see the inside and outside of a "room" then I suggest modeling 4 seperate walls (if it's a square/rectangular room, and if it's square then you can simply duplicate one wall 4 times, line them so that they evenly line up with each other, once that's done cut a hole in one wall in order to make a doorway.) By doing it this way, the outer faces of each wall piece will be seen and you can simply combine the objects in order to move it around easily.

ok, cool thanks a lot now 1 more questing, is there a way to instead of inverting faces so there seen from inside do something where there seen from inside and out, im thinking mabey just creating 2 models 1 inverted and one normal and aligning them