1) Open the Google Wallet app, go to settings, and select "Reset Google Wallet". Exit the app.
2) Go into the phones settings, apps, find the Google Wallet app, tap on it, and select Clear Data. Then uninstall the app (or updates).
3) Re-install the Google Wallet app.
4) Make sure your NFC is on, and launch the Wallet app
5) Follow the set-up instructions to activate the app on your phone. Check to see that everything is functioning.