If you are getting problem with your keyboard then its better to change it or change to default one. If you want to restore the keyboard then here are the steps to follow:

• First, go to Settings > Personal > language & Input
• Next move to Keyboard & Input methods
• Now, tap on Default and choose from the installed and active keyboards.
  

Now you can also change the keyboard by downloading a new one like Swiftkey keyboard.
Check out more on: https://www.androiddata-recovery.com/blog/restore-android-keyboard