Proscan 42 in tv....has a very thin line about 4 inches from the bottom of the screen. we had the tv for almost 3 years. this just started last night. can it be fixed?

Anything can be fixed, short of it being totally destroyed. The question is can it be fixed in a cost-effective manner? Today's TV sets are manufactured for a three-year lifespan....regardless of what the manufacturers say. They are made with minimal-tolerance components, and are designed to fail in the 2-4 year range. Most make that, some don't even get out of warranty. The manufacturers take the risk because it is more profitable for them to make some warranty repairs in order to get the repeat buyer in 3 years instead of 10. If you got 3 years out of you set you did well. Some try to repair the sets themselves; some are successful, many are not. These devices are delicate and often in the process of fixing one thing, something else gets broken. You can try for repairs, but you are most likely better off buying new, and consider this when buying.....look for features you want NOW and not in the future, since by the time those feature are needed, you will be once again in the market for a new set. One additional piece of advice; to help these new devices last longer, buy and install a UPS to protect them from voltage variations and power surges. Surge suppressors alone can help, but they don't respond to voltage variations that often occur in electrical service. These are often the killers on these devices.