When writing short messages with Sony Ericsson mobile phone, you can't write letters and numbers, and the # key is useless.

You must press the pound symbol for a long time. Did you lose the font settings? There is a more on the right side of your message, and the input options can be selected. It is estimated that the input method of your mobile phone is only pinyin! There is a language in the phone settings. Open the language settings, there are input settings. See if you only choose pinyin. If you only have Pinyin, you can only press Pinyin anyway. Just tick the rest of the English and the numbers. I'm Sony Ericsson W580I for your reference.

It may be that the tic-tac-toe key is broken, or it may be that the internal contact is not pressed.