how to synch my iPhone anki to my iPad one
You need to sync both your devices with the same AnkiWeb account. Cloud Sync - AnkiMobile Manual
On your phone (where it works), go to 
Preferences > Syncing – and see what email address you used there. If you don’t remember your password, you can reset that through your AnkiWeb settings page – https://ankiweb.net/account/settings – and then update the password on both devices.