I bought a Dell Inspiron 1545 laptop in March this year and the AC adapter has recently stopped working, the light doesn't even come on when you plug it in. At the moment I can't use the computer at all because the battery has run out and I can't charge it up. Is the adapter covered in my warranty? (I can't find the information)

If it is then how do I go about getting a replacement? And if it isn't then what adapter do I need to buy?