@Soumaia All plans reset every 30 days and are never on a set day of each month as noted earlier, so depending on your renewal date, it's possible you've already depleted your plan allotment.
First check what's available under My Data/Add-ons on the overview page. If the data line is missing, then you either can wait until next renewal or purchase add-on data to tide you over. Add-on data costs $15/1GB but any remaining data from it will roll over every cycle until depleted. Also you need to add funds first and then back to buying the add-on if you go to this option.
Check that you haven't set the data limiter on your phone. You would also need to sync the dates of your renewal to your phone's data to get a more accurate read of how much data you maybe using each 30 days.
