They can last a LONG time, especially the ones with LED backlights (which weren't super common 7 years ago, though).
What usually dies on a regular LCD is the backlight- either the power supply or the fluorescent tubes themselves. The power supply is usually an easy fix, if you are sure that's what it is. Otherwise, you wind up "throwing parts at it and praying." Newer LCDs are so cheap and so much thinner/lighter than the ones made just 5 years ago, though, I'd probably just replace.