Hi @aganz18, let me see if I can help out here!
Your post has been translated to English as this is an International forum, please post any replies in English and it will be easier for me and other users to assist you.
Have you tried clearing the data for the messaging app? This will not erase any previous text messages, but it will reset all settings for the app which might do the trick. To do this, find and tap Settings > Apps > Messaging > Storage > Clear data > Restart the phone.
Another thing that you can try is to reboot your phone in safe mode to see if the messaging app works better there. All apps downloaded from Play Store is temporarily deactivated while in safe mode and by doing this, you can see if this behaviour is caused by a downloaded app. For more information on safe mode and how to use it, click here.
If the behaviour persist in safe mode, I suggest that you try to to repair the software using Xperia Companion. Keep in mind though that the software repair will erase all user data from the phone, so remember to do a backup first in order to prevent data loss.
Try these measures and let me know how it goes!
