I need to change my card number on my pay pal

SOURCE: change my reference credit card on pay pal

As per Paypal:
Question : Can I register a credit card on more than one PayPal account?
Answer : No. For your security, you can register a credit card on just one PayPal account at a time. You may, however, register several different credit cards on a single PayPal account.

If your credit card was registered to a different PayPal account, you need to log in to the previous account and remove the card before adding it to your new account. To remove credit cards from your account click Profile at the top of the page and click the Credit/Debit Cards link in the Financial Information column.
Question : What if I forgot my email address?
Answer :

1. Go to the PayPal homepage and click Problem with login?.
2. Click I don’t know what email address I used.
3. Enter up to 3 email addresses you might have used to sign up for your PayPal account.
4. Enter the code shown in the image.
5. Click Continue and follow the instructions.

1. Go to the PayPal homepage and click Problem with login?
2. Select one of the following:
   • If you know your email address, click I don’t know my password. Then enter your email address.
   • If you don’t know your email address, click I don’t know either one. Enter up to 3 email addresses you might have used to sign up for your PayPal account.
3. Enter the code shown in the image.
4. Click Continue and follow the instructions.