Flat screen TV's, both LCD and plasma, have very sensitive screens. In some cases, damage to pixels or screens can be repaired, but in many cases screen damage can't be fixed and you'll have to replace the set. It is important to take all precautions and properly maintain your flat screen TV to prevent damage.
Once pixels on a flat screen TV or the screen itself have been damaged by trauma they are extremely difficult to repair and often times require the services of a professional or replacement. Trauma can occur while moving or transporting the television, or placing it in a high traffic area. Take all possible precautions to avoid touching the screen -- let alone hitting it with your hand or a object. If you're moving the TV, manufacturers recommend covering it with a soft cloth to prevent scratching and storing the TV upright, rather than flat or on its side.
Flat screen TV's use a considerable amount of energy when compared with other home electronics. Fluctuations in electricity levels, either from problems with your energy provider or from connectivity issues in your home, can fry circuitry and damage pixels. Using a surge protector at all times helps to mitigate this threat.
Burn-in occurs on a screen when a static image is prolonged on the screen for an extended period of time -- the pixels on the television become stuck in a fixed position, leaving a shadow or permanently displaying the image. Although manufacturers have largely added features to eradicate burn-in, it can still occur with menu screens, gaming, or when borders are present around programming. Be sure not to leave a static image, like a paused movie, on the screen for extended periods of time, and don't leave menu screens idle for too long.
Extreme heat, cold, humidity, or moisture can permanently damage the display a flat screen TV. Humidity can short out circuitry inside the TV, while extreme heat or cold can disrupt the ability of the pixels to change color properly. If you must move or store a flat screen TV for extended periods of time, it's best to keep it in a climate-controlled situation.