Need permissions, screen overlay

Problem started when trying to take pictures. Phone needed updates for a while and had been putting it off. Did all updates and still having issues. Wont open i think almost all apps. It says go to settings and apps and accept permissions and either app wont be there to accept or when it is there, it will tell me to go do something else first and cant get there. I assumed its a software problem, because it said "screen overlay detected" but searched in my settings for it and cant find where to fix it....