I'm sorry to hear your iPad isn't activating. I'd be curious to know which model it is and what the last iOS version you installed on it was. Regardless, here's what I'd recommend:
1. Try restarting it: Restart your iPhone, iPad, or iPod touch
2. Try plugging it in to a computer with iTunes to attempt the activation
3. Try performing a recovery mode restore: If you can't update or restore your iPhone, iPad, or iPod touch