How do I get my data to work

Are you connected to cellular data or are you referring to data while you are connected to wi-fi? If cellular, make sure that cellular data is turned on in settings, and if still does not work, contact your cellular carrier. If wi-fi, is this your network or someone else's? If someone else, check with the network owner. If yours, do you have other devices that you can check to see if wi-fi works on a different device?

Wi-Fi data, or cellular data?

What model iPhone?

What iOS version?

Has it worked in the past?

Can you make and receive phone calls?