Why won't my iPhone screen rotate sideways when I rotate my iPhone? - 2

I asked one of my friends about it and he said that the screen lock might be on. So I a checked information ok the screen lock and found out what it was and everything and turns out my screen lock isn't on. If it was on that twisted arrow thing was suppose to show at the top right hand corner of my phone.

So since it isn't the screen lock can any one give me any advice on how to fix this problem. Oh yeah and one more thing, I dropped my iPhone so I think that could be it but my iPhone is working fine it's just that one problem.

So I would really appreciate it if you could help me.

Added (1). @ Peep - I tried that. It still doesn't work.

Try playing temple run then tilt your phone sideways if the character doesn't move its a hardware problem go to a phone shop to get it fixed. If it does then just go to your settings and look under display and check the auto rotate screen function.

The same thing happened to my mom. I don't remember exactly how me cousin fixed it, but it had something to do with settings.

Double tap the home screen, then flick it to the right and the should be some portrait thing