It should be in your email! Our system emails a tax receipt within minutes of successfully processing a donation, so if you don't receive it, search your email for the word "Pledgeling" and be sure to include your junk or spam folder.
If it's not there, it's possible that you mistyped your email address on the donation form. Submit a support ticket at help.pledgeling.org with the name you donated under, the email address you would have used on the donation form, the organization you donated to, and the approximate date and amount you donated. If you can provide the exact amount and date, along with the last four digits of your credit card number, that helps a lot. We don't necessarily need all this but it can help cut down on back-and-forth emails if we can't find your record right away.