If this is a cellular model, try removing the SIM card from the SIM card tray located on one the long sides of your iPad.
You may need something like the end of a paperclip to open the SIM card tray.
If this doesn't work, try resetting your MODEM/router by unplugging it for 10-15 seconds, or so, and then re-plug it in and let the MODEM/router re-cycle up.
Good Luck to You!