How can I fix my Daewoo DR-2100P DVD recorder?

Having used the above DVD recorder for several years to watch DVDs, recording images from my camcorder to DVD and the odd copying from TV programmes suddenly I can no longer get any picture on the TV screen from the recorder. I have tried all combinations of input on the TV (it used to go through AV 2) and input in the DVD itself. I am wondering if the recent changeover to digital TV has upset something but without getting a picture on the screen I cannot retune via the setup buton. Batteries in the remote are fine. Has anyone else experienced this and how did they fix it?