I received a product from e-bay that I have not ordered.

[marnotom!]

eBay itself doesn't generally send out stuff, so you probably didn't receive something "from eBay."  eBay does make eBay-branded shipping supplies available to sellers, however, so you may have received something from someone using those shipping materials without the item being connected to an eBay sale.

We really need to know a bit more about what happened here.

[3islanders]

In addition to the previous suggestions, and yes, more information about your situation would be helpful -- does anyone else have access to your eBay account?  Is it possible that a child/spouse/roommate ordered something?  There should be a payment record for that as well.

[reallynicestamps]

Is there anything in your Paypal or credit card statements that indicates you have been charged for it?

Was there a return address on or in (packing slip) with the name of the seller/sender?

As I understand it, if you receive something that you neither ordered nor paid for, it is a gift.

You can keep it and there is no need to pay for it, return it, or do anything about it.