A Roy Lichtenstein painting that vanished 42 years ago has re-appeared in a Manhattan warehouse.

Now valued at $4 million, the pop art picture was sent out by gallerist Leo Castelli to be professionally cleaned when it went missing.

Castelli's widow, Barbara, was notified by the Roy Lichtenstein Foundation when the work, titled "Electric Cord," was offered for sale to a gallery by the self-proclaimed "owner." The gallery contacted the foundation for authentification.

Barbara Castelli has filed papers in court to halt the sale of the painting pending a court hearing.