My battery is running dead . Can I have it replaced ?

Yes, the battery for this watch can be replaced. Timex estimates that the battery should last 2-3 years, but that assumes an "average" use of the Indiglo backlight. If you never use the backlight or audible alarms, your batteries would have lasted longer; heavy use of both would have run the battery down more quickly.
If you want to replace the watch battery yourself, you'll need a very fine philips or flathead screwdriver, the new battery, and a bit of patience. It would also be helpful to have a pair of tweezers, but that's not absolutely necessary. If you carefully look on the back of your watch, Timex usually lists the battery type so that you can buy a replacement battery without first opening the watch. If you can't figure out what the numbers mean, take it to a jewelry counter at Target or Walmart, and they should be able to help you decipher it. I don't know which battery this specific watch takes, but many Timex watches use a #1620 or #2016 3v battery. Look for a number like that on your watch back.
To open up the back of the watch, open the strap so that you have good access to the back. If you have a steel band, you might need to slip out one of the adjustment pins to separate the band into halves. Yes, you might be able to take the back off without this step, but it makes it a lot easier.
Place the watch face down onto a soft surface. I like to use a dark towel, so that if I drop one one of the tiny screws you'll be dealing with in a minute, they won't bounce and you can easily find them again.
Use your screwdriver to loose the back of the watch, one screw at a time. I find it very helpful to loosen a screw, then use the tweezers to pick it up out of the hole. These guys are tough to grab with your fingers! Put the screw in a safe place, then carefully remove the back of the watch. A little black neoprene gasket may be stuck to the back or be floating around--don't lose that!
You should be able to see where the battery is kept. On most Timex watches, there's a metal shield covering the watch and completing the power circuit. Using your screwdriver, gently pry the tabs of this shield away from the watch movement, one tab at a time. Try very hard not to snap off any of the little plastic anchors. On a Casio watch I recently serviced, I had to remove the movement from the watch to get at these little tabs; I don't remember ever having to do that with a Timex.
Once the shield is loose or removed, the battery should slide right out. Replace the battery, and gently snap down the metal shield. Turn the watch over to check whether it's working again. If it's not, you may have to push a little "reset" pin on the watch movement to clear the registries. The back of the metal shield usually has instructions on where that little pin is located. If the watch is already working, you won't need to do this.
Closing up the watch is the reverse of what you did to get it open. Make sure the neoprene gasket is back in place--that's what's keeping sweat and water out of the watch--and carefully set the cover back in place. Tighten the screws in an "X" pattern--i.e., top left, then bottom right, then bottom left, then top right. I get all the screws loosely screwed in before tightening them down in earnest. This watch has a plastic case, so you want to tighten the screws snugly, but not over-tighten them so that they strip out the screw hole.