My phone's data is on but I still can't connect to any internet because it says I have no Network connection. Plus I cannot receive or send any messages that are MMS and need to be downloaded.
you might need to manually add apn settings. search in Google for "APN settings for [name of carrier]"
(add the name or your carrier example would be at&t it Verizon ect.)
then when you have results of what the APN is supposed to be, go into phone settings>more networks>mobile network>access point names>press the +on top right, and add the settings
Facebook
Twitter
Instagram