Log into self-service and ensure you have data remaining. If you do ensure your phone has data on and your apn settings are correct. You can also try rebooting phone and resetting network settings.
Have you logged into your cell service account to see if you have any data remaining on your plan? Make sure you do so in secret/incognito mode to ensure you are not viewing the cash version of your cell service account. Have you checked your APN or updated your carrier profile if you have an iPhone?
