Hi @Margo3000, sorry to hear about this.
I have translated your question 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.
Are you able to receive SMS but you can't send them or can you send them but not receive them? There are very few settings that can be changed in the device since the number for the Messaging central is grabbed from the SIM card and this can't be edited.
A good test to do is that you ask a friend, colleague or family member if you can borrow their SIM card > send a text message to that number and see if you can both send and receive the message. If you can, get in touch with your operator.
Let me know it goes!
