I bought a protable tv that doesn't work at all. Screen is black and there is power going to it. No volume either. Contacted seller's e mail to no avail....what recourse do I have?

If this purchase was through ebay, go to the ebay page under purchase history, and (under your purchase) contact seller to make them aware of the problem.
If you still don't hear from them (or have already done that) then under the same listing, click resolve a problem. It will contact seller for you and create a case (I am assuming this was listed as a working item) for item not as described. There is a link below for creating a case.
I would also recommend using the ebay learning center to go through the other policies when you make purchases on ebay.

http://contact.ebay.com/ws/eBayISAPI.dll?CustomerSupport