48 day of cycle no period yet?

Possibly pregnant. The number one reason for not having a period is being pregnant. Every physician would recommend you take a home pregnancy test to determine if this is the case. If you are not pregnant then there are a number of issues that it could be, such as a thyroid issue, or polycistic ovarian disease, etc.
Preg test? Obviously check a pregnancy test. Many factors could affect your cycle including hormonal changes, medical issues like hypothyroidism and stress. Follow up with a doctor for simple blood tests.