My face color is much darker than my body's color. sunscreen will protect further damage. but how can i get my own color back?

Multiple options: IPL does a really nice job of lightening sun damage with no down time. It does require regular (every 3 months or so) treatments to maintain results. Some chemical peels can lighten sun damage. Fractionated laser does a really nice job of lightening pigmentary issues, but does require some downtime and may not work if your skin is dark. Hydroquinone and lightening creams are other options.