Problem with importing Blender to Unity

Hey Everyone, I have problem with Blender this time. I create a level map quickly for university purpose using to planes, and extrude tool to make two floor’s. I tried to save file as and in my unity Model folder same as I did before with .blend extension but it didn’t show up there at all. It is said that is there when I try to save again but when I open Unity is not there. I try to save it somewhere else and then import it but it doesn’t work either, it does show file this time but can’t put it to the scene. I tried also exporting as .FBX file and then importing to the unity, however when I do that floor disappears when I put to scene. could anyone tell me how to fix it ? Thank you.

Are you perhaps saving it in Edit Mode? If yes, please change to Object Mode and then save.