When an attempt at a purchase is made you may see a pending charge on your statement. This is called an authorization hold. If the purchase is successful, the charge will go through after around 24 hours.
If the purchase is not successful and you did not receive an order confirmation, then the charge will be removed from the account, typically after 48 hours, although this can take up to 10 business days depending on your card issuer. Please contact your card issuer for further info about authorization holds.