The best place to look is on the website where you purchased the voucher, accessed on a computer. It is sometimes also possible to look it up through an app, or in your email.
You should be able to find your codes by logging into your account on Groupon.com or LivingSocial.com
If you have any difficulty locating your voucher or codes, you may need to contact the customer service team at the website where you bought the voucher code. They should be able to help you from there!
Please note that, for your security, your purchase details at external companies like Groupon and Living Social are not accessible by Paint Nite staff, so we are not able to look up missing codes for you.