Why won't my iPhone screen rotate sideways when I rotate my iPhone? - 1

I know this is the wrong section but you guys are awake and this is serious.

Ok so 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.

I double tapped the gown screen button and then flicked to the right and I unlocked and locked my screen and kept trying but it still didn't work.

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.

Btw there are some games where you can only play sideways and it works for those games but that's because in those games you can ONLY play sideways.

I have a strange feeling it has to do with me dropping my phone but everything else is working fine.

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

Added (1). @ Brooke - in case you didn't read I already said that in the 3rd paragraph and it didn't work.

Is this on the home menu? If so, I don't know what to say.

Press your home button quickly twice, now swipe the screen that popped up at the bottom. You will see a semi circle with a lock in the center. Press that and it will unlock. You've locked your phone from switching to portrait orientation---> Oops! Sorry! Check your settings if you have an update available? Sometimes things go wacky when you need to update. Dropping may have messed up a sensor inside try playing a game that requires tilting and see if it picks up your movements