i still have ios 9 and im trying to update to the latest ios 10 but it said it cannot verify update because im no longer connected to wifi but i am what can it be?

Try looking for and deleting the installer file that may have been downloaded:

1. Open the Settings app on your iDevice and go to “General”.
2. Select “Storage & iCloud Usage”.
3. Go to “Manage Storage”.
4. Locate the nagging iOS software update and tap on it.
5. Tap “Delete Update” and confirm that you want to delete the update.

Once you've done that, restart your phone and try again. I think it's possible that, a long time ago, you downloaded the installer for iOS 10.2.1 and now, when you try to update, it's trying to use that, which won't work.

Best of luck.

Where did you find iOS 10.2.1? That is no longer being signed by Apple. The current version is iOS 10.3.1.

Try rebooting your device

@luis wrote:

Alright thanks so much it worked

I'm glad to hear that!