I mean, what did you think would happen

haha!! I have done that before but I actually remembered the setting to change it so it didn't bother me.

Save you some time and possibly a service charge from those greedy bastards at Apple: Settings > Ninth option down should be the General section > Thirteenth option down on that page should be Language & Region > First option is iPhone Language. Select that, then find English (英語, or Eigo) > Select it, hit Done (upper right corner of your screen, text is blue) > Hit the first option bar that pops up on the bottom of your screen and voilà! Your phone is fixed. This may also be useful to anyone else who might find themselves in this situation with an iPhone.

I often put my phone in Spanish to show my Hispanic stepdad how to use his phone.

When I got my first smart phone, I accidentally changed the language to Korean! It took lots of time and fumbling around to fix it since I couldn't put the characters into a translator lol.

you should YouTube how to fix it. I'm sure there's a guide. Good luck!

Oops. I did that to my phone once, but with German cause I thought I knew more than I did. Relatively easy fix.

How exactly did you expect that go?...

If you have a backup of your phone from before you should have no trouble restoring it back to its previous state.

アホ！