HALF OF MY SAMSUNG 46 IN TV IS DARKER THAN THE OTHER WHEN I TURN IT ON AND DOESNT COME ON FOR A COUPLE OF HOURS. WHEN IT DOES ALL COME ON IT FLICKERS WITH BLACK PATCHES COVERING IT STARTING AT THE BOTTOM AND GOING ALL THE WAY TO THE TOP

SOURCE: Half Screen went black

Try to replace the Logic board.

SOURCE: 46" Samsung TV loses sound.

R U using HDMI? If so that be the problem.

SOURCE: Complete black screen on samsung 46 inches

Yes, you do need to get the LCD repair before the warranty expires. Call the manufacturers to find an authorized service center near you.
Good Luck.

SOURCE: Top half of screen going black.

I've seen this or something similar to this problem on an old lcd screen. The bulb haden't burned out but the system was no longer getting proper 5 volts to the processor chip that processed the image. I ended up desoldering the voltage regulator and soldering a new regulator in it's place it was one with the same amperage so I put a heatsink on it to reduce the chance of another failure.

SOURCE: samsung 46" HDTV power keeps turning off after a period of time

Panal damage is a possibility however, you may also try to have a tech replace your mainboard since you have sound.