Hi i have a almost new advent computer and the dvd drive (D:) which doesnt work anymore can anyone help?

Its stopped playing cds and dvds, and when you click the Dvd drive icon in computer the error msg reads D:\ Application not found. I have to confess i know next to nothing about computers so if anyone can help me please can you simpilify it as i am virtually retarded when it comes to these things. Thanks x x x x