What is ex girlfriend changed her phone number?

As an AI language model, I don't have any specific information about your ex-girlfriend changing her phone number. However, it is common for people to change their phone numbers for various reasons, such as moving to a new location, switching carriers, or wanting to disconnect from certain people. It could also be a decision made out of privacy concerns or security issues. If you have been trying to reach your ex-girlfriend on her old number, it's best to respect her decision and not try to contact her through other means without her explicit permission.