For Online Computer Support, Ask a Computer Technician
Have you tried cleaning the lens? If the lens has the smallest particles of dirt or dust, it could stop your DVD player from operating correctly. A good blowing, with a dust remover made for computers, followed by a cleaning, with the cleaning disc made especially for cleaning the lens of the laser reader in the DVD player, shold solve your problem. If that does not help I am afraid the DVD player needs to be repaired by a qualified electronic tech or replaced.