I’m not receiving a code via text message or phone call
If you chose to receive codes by text message, make sure your
service plan and mobile device supports text message delivery.
Delivery speed and availability may vary by location and service provider. Also make sure you’ve got adequate cell signal when you’re trying to receive your codes.
I can’t get verification codes or lost my phone
If you’re a Google Apps user (for example, your email is
yourusername@domain.com), you have two options:
Asked to provide verification code despite checking 'Trust this computer' box
You might be asked to give your username, password, and a code multiple times despite having checked the box next to "Trust this computer" at sign-in. Usually this is because your browser does not have cookies enabled, is set to delete cookies after a certain period of time, or is set to delete cookies every time you quit the browser.
'Trust this computer' option doesn’t work
For computers you trust, Google recommends you select the "Trust this computer" option when you are asked for a verification code. When you check this box, you won’t have to enter a code every time you sign in to your account from that computer.
Delivery speed and availability may vary by location and service provider. Also make sure you’ve got adequate cell signal when you’re trying to receive your codes. 
