Hi, this often happens when you have a weak processor for new tasks and applications. However, this has happened to me because of a natural breakdown because my phone was accidentally dropped. To find the reason why your phone hangs and lags screen you can find here: https://howly.com/article/the-screen-of-my-android-phone-screen-is-frozen-how-can-i-restart-it/. The guys have tried to describe in detail all the causes in this article and have done a great job. But my advice is that if you need help you should contact a repair service.