How can I fix my Mikomi LCD15796?

I have only had this TV 1 day and I have a problem that I cannot solve.Upon setting the TV up the picture quality is very poor some of the picture looks negative,I have tried all the settings but nothing makes any difference.I have tried everything I can think of to sort the problem any ideas please.Also when I connect a dvd player to the TV I get an awful picture and no sound.