I had a paypal test account. After changing the paypal website we can't login to the paypal test account. But we can pay using this test account from our site. We can't access the paypal account for getting payment details. How can we access the account
When you create your account at the new developer.paypal.com site it will walk you through importing any sandbox accounts you had previously configured at x.com.
If for some reason that doesn't seem to be working for you and that account just isn't giving you what you need you could just create a new one from within your developer account and use that instead.