If you activated 2 Factor authentication, you must enter the current token generated by "Authentication" App (powered by Google) every time you log-in.
If you lost access to the app or you deleted it, please follow these steps.
If you are trying to log-in and it the web page is not reading your token ("invalid token"), please follow this advices:
1. Make sure that the time in your smartphone is set in automatic. This allows a correct synchronization with Google server.
2. Make sure you have followed ALL the steps required when you activated the authentication. Especially, have provided the token asked in "my account" after you scan QR code.
3. We suggest to close the browser and the app. First open the authenticator and then open the browser. Try to log-in again.
4. You can try using other browsers (e.g. Google Chrome).
5. Enter the token without spaces between the numbers.
If you still have problems with the token, send us an e-mail to firstname.lastname@example.org so we can help you.