it says unfortunatley, system UI has stopped

If it is rooted and you do not know what you are doing, you might have deleted an odex file that patches that. Otherwise the systemui settings are corrupt and you might have to do a factory reset.

my phone kept syaing that and it finally shut down and wont turn back on

I use a lg Phoenix 2 and when I start up the phone it says unfortunately, system ui has stopped. I can't do anything on the phone. How do I fix it.

Just recently came up on my LG life’s good phone I literally don’t know what to do because I need to to work because my dad contacts me a lot on the my LG phone whenever I’m out with my mates

I have had this problem too. The error message "Unfortunately, System UI has stopped" pops up around every five minutes, and I can only access the first 5% of my phone. The battery charges fine, but the phone itself doesn't allow me to use the device because of the error message.