How to get a good picture on a samsung le40a436t1d?

For some reason my tele lost all its original settings this week and I cant seem to get the picture any good at all. I ve looked on forums and websites and tried different suggestions but the picture is still pretty dud. Its a samsung le40a436t1d 40 inch lcd. Does any one know how to get a decent picture. Cheers|||Set contrast to 100% and all the others should be 50%...then tweak it to your liking.