A common problem for Apple iPhone users is the microphone is missing from the keyboard.
Users expect it to appear in the lower-left corner of the keyboard when using any app.
There are a couple of things you could check to solve this issue.
Fix 2 Enable Siri
Enable Siri under parameters > Siri > On >Enable Siri.
This happens frequently to me in the Google Hangouts app.
Close, the app by double-tapping on theHomebutton, then swiping the app upward off the screen.
From there, start the app again by selecting the icon on the Home screen.
The microphone should then appear on the keyboard.
From there, switch the Slide to power off option.
Remove the keyboard app or switch to a different keyboard to get the microphone back.
