Lucia’s sister is right, things do change based on whether you used the ring correctly or not.
If you have used it correctly, following all instructions, and you have not taken any other medicines, it is very unlikely that you are pregnant. In this case, you can continue to use the ring as usual. However, in the case that the pseudo-menstruation fails to appear two times in a row, you may be pregnant. Immediately consult your gynecologist. Do not start using a new ring until he/she has ruled out pregnancy.
In the case that you have used the ring incorrectly, lack of pseudo-menstrual flow could signify the start of a pregnancy, which must be verified by the gynecologist. Contact him/her before using a new ring.