Help Pllleaseee

I have Boost/ Sprint phone called the Hydro Kyrocera. Out of nowhere it is keeps popping up a black box that say 'unfortunately contacts has stopped working' or "unfortunately *fill in app name* has stopped working. It keeps popping up this box, and will not let any app work. Ive tried turning it off and on, updating it, the only thing I havent done yet is the factory reset, I was kind of saving that as a last option. Any ideas or tips? please and thank you!