Hi @Blanca1981 sorry to hear about this.
The first thing that I would suggest that you try is to reboot your phone in safe mode to see if the phone is able to detect the SIM card there. Safe mode is a troubleshooting mode where all apps downloaded from Play Store is temporarily deactivated 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 phone still do not detect the SIM card while in safe mode, I would suggest that you do is to try to perform a software repair using a computer and Xperia Companion. Please note though that a software repair will erase all user data, so remember to do a backup of your user data first.
If none of these measures manages to improve the functionality of the SIM card reader, I believe that the best thing to do is to get in contact with your local support team in order to have the phone sent to an authorized service center. If you have any questions regarding the service such as service routines, warranty and consumer laws, these questions are best answered by your local support team as well.
Try these measures and feel free to keep me posted with the results!
Try this and let me know how it goes!
