taybo style you are not giving us a lot to work with. You should at least tell us what you have tried to fix it etc. Anyhow start with the troubleshooting flowchart for your particular set.
[image|1207800]
You will always have to check your menu settings and try every input to see if the results are the same. Most likely you will need to add some images of your boards etc with your question so that we can point out where components are located etc. For that you wan to use this guide [guide|21499]