Smartphone keyboard not working

I have a Samsung Galaxy Core Prime. It works fine, if slow as all **** sometimes. However, today i had to restart it to try and get it back up to speed (this sometimes works), and the keyboard has stopped functioning so I cannot get into it. I have restarted, I have fully charged it and restarted it again and still nothing. When i click on the bar to put in my password, nothing comes up. I click emergency call and then the error message pops up saying the keyboard has stopped working. I have no idea how this phone actually works or how to diagnose and fix the problem at this point.