If you can see emoji keyboard in notes app. Congratulations, you have enabled the emoji keyboard. But some users set they can't use it on other apps. You can try the following fixes:

1. Reboot the iPhone, iPod Touch. Long press the power button, slide the slider to turn off the phone completely. Then press the button again after the screen is off to turn it on again.

2. Add more foreign language keyboard. To toggle to the emoji keyboard, actually you need the "globe" icon on the keyboard to be shown. For some unknown reason, may be bug, the icon will not be shown on the keyboard in some apps if only English and emoji keyboard is enabled. So I suggest you to enable more foreign keyboard, suggest Chinese keyboard or Japanese keyboard, to see if the "globe" will come out. If it works, I think you can disable these keyboard afterwards.