You can try one of these things?

I forgot my email address.
You can retrieve or change your PayPal email address if you can confirm the following account information:
your name
your ZIP code
your phone number
your credit card number
Here’s how:
Go to the PayPal website.
Click Problem with login? in the Account login box.
Click I don’t know what email address I used.
Enter up to 3 email address you may have used to create your PayPal account.
Select the option to I want to create a new password or select I know my password and want to log in.
Enter the characters shown in the image in the security text box, and click Continue.
Follow the prompts to complete updating your email address.
Enter your new password twice, and click Submit.
Link to Paypal Help Center

What if I forgot my email address?
If you can’t remember the email address you use to log in to your PayPal account, we can help you.
Go to the PayPal home page and click Problem with login? under the Log In button.
Click I don’t know what email address I used.
Enter up to 3 email addresses that you might have used to sign up for your PayPal account.
Enter the security code and click Continue.
If we match your email address to your account, click I know my password and want to log in.

If none of the email addresses match, you can enter 3 more email addresses or follow these steps:
Click different method.
Enter your account information.
Enter the security code shown, without spaces, then click Submit.
The email address you used with your account appears in the Account login section of the page.