my iPhone 5 says it has no camera can someone please help

Today when I was supposed to take a picture of something i couldn't find the camera app. i searched for it but i didn't find it. I had alredy downloaded an other camera app and when I tried to take a photo the picture was black and a banner said "use a device with camera". i tried with snapchat but it only showed a back picture, then i tried instagram but there I wasn't able to take a photo. This is extremely frustrating because I'm on a training camp in qatar and I really want to take photos of all the great buildings. SOMEONE PLEASE HELP ME!!!