It is definitely a difficult situation to be in. First and foremost, it is important to remain professional and courteous in any communication with the new employee, even if they have blocked your friend. It may be worthwhile to try reaching out to them through other means, such as email or a different phone number.

If all attempts to contact the new employee fail, it may be necessary to involve management or HR to assist in the retrieval of the uniform. It may also be helpful to review the company policies regarding employment termination and uniform return, and consult with HR to ensure all necessary steps are being taken.