Don't worry, it happens!
If you think you'll find it again, immediately open your app, switch to the "Card" section, and press the "Freeze my card" switch, to prevent anyone from using it in the meantime.
If you would like to order a new one, go to the "Card" section, and press "Replace my card". Remember, while you wait for a new card, your old one will be frozen and you won't be able to use it.
If this is the first time you've lost your card this year, we'll send you a new one for free. If you've lost it more than once, we will need to charge you $6.00 to print and ship you the card