Re: The camera button has gone from my screen.
OS is win8 and there is no lumia camera and I don't remember seeing anything about a microsoft camera. I've only had the 640 for two weeks and photography is only a minor thing. I've never used a smart phone before this.
Okay, so first thing is that you can do is find a place with good wifi. This is to help you update your phone to the latest OS version.
[TITLE]To get windows 10 mobile[/TITLE]
Go to store, search for an app called Upgrade Advisor
Install it and run it. It will check whether there are nay updates for your phone. If yes, go to settings >update and install the updates. After the upgrade is finished (can take a couple of hours) check for any app updates in store. Finish all that and then check camera
In case you don't want to install W10M, you can just check in store if there are any updates for the camera and install that. Additionally, you can also install other camera apps like camer360 or proshot or lumia camera