How to fix Login error on Facebook and messenger apps!!

I had this problem for a month and had to use safari and my laptop. One day I logged out and I couldnt get back in because it kept saying login error. I deleted the apps and reinstalled many times but didn’t work. I reset my settings but didn’t work. I erased the whole iPhone settings and backed up with iCloud and didn’t work. BUT THEN I FIXED IT!!!!

I erased my iPhone again but I started as a new iPhone, I downloaded the apps and logged in and it worked!!!! So then I backed up with iCloud and got all my photos and emails back!! Yay! I hope this helps someone. I came here for help but couldn’t find anything so figured it out myself now I want to help others because Facebook is so useless!!! You’re welcome :)