My mobile phone belongs to Nokia. When I read a short message, it is too long. There is no response when I press the down button. I can't see the message below. What happened?

Either it is poisoned or there is something wrong with the system. You can press *#7370# to restore the factory settings. That will delete the things stored in the phone and the settings of the phone. You'd better make a backup of the number and software and save it on the memory card first. I've used it. It's very useful. In the past, many small problems on mobile phones have disappeared. I suggest you try. If not, take it to the warranty. It should be no problem.