Does it need a new battery

Replace the battery, the solar part doesn't mean it charges from the sun it has to do with the movement of the arms (I'm not %100 what that means) I just know it doesn't charge by the sun or any other light source.

You need to replace both batteries in side and sit it in the sun to charge the interior one there's two batteries

yes, this watch uses battery, you had to replace it with a new one. you had to bring it to watch service center because they have what you need for your watch. i hope I solved your problem.

Do you mean, you haven't been wearing that watch but to put it in the drawer for a long time?
If so, to recharge the battery, just put your watch outside or anywhere it can catch the sun ray or day light. After few hours or about a day, the battery has been re-charged and your watch will work.
If it still doesn't work after doing that, buy a new watch. Don't bother to repair the watch or to replace the Eco-Drive battery, because of the cost.

Is it SOLAR?
I have a Casio Pathfinder, SOLAR, ATOMIC! They have a permanent battery!!!
It must be exposed to the sun occasionally to charge. If yours has nothing on the display, try putting it out in the sun for a day. Put it in a window, sitting on a window sill. Depending on how little charge it has, it may take as long as three days to charge.
Otherwise, the alternative is calling Casio, getting an RMA and sending it to them for a battery replacement.

Perhaps it got too hot. The operating range for watches seems to be zero to sixty degree centigrade.

If left in a very sunny position it could have exceeded the higher temperature. If it doesn't recover by itself, then try a new battery.

It might be instructive to talk to the maker (address at Citizen.com) to confirm my suggestion before replacing the battery.

this watch requires no battery. It uses solar cells. my watch did this as well. to make the watch functional again my advice is to not wear the watch for one day and place it near a window that gets a lot of sun.

The Citizen Eco Drive watches use special recharchable batteries.
I started collecting a couple of watches and I noticed sometimes a jeweler replaces them with an ordinary battery. The watch will work and at the same time it will try to recharge this one until it explodes! In newer models they made it harder to use the non-rechargable ones by adding a special connector or clip to the rechargable battery types.
Okay, if you say your battery goes bad, or the watch does not run? It may have lost the charge over time. First thing to try is to leave it on the window sill so the dial is in the sun. It will start ticking, but please leave it out there for 3 days to a week. The seconds hand will tick irregularly in steps of one and two seconds, to show you it wants you to readjust the time, as it knows it has lost time. Adjust the time and it should run smoothly.
The seconds hand should run in single second steps, if it takes steps regularly, but every 3 seconds or so, it tries to tell you that its power level is going down. It will be able to continue for one or two days, but you should get it into the sun more often.
Charging the battery under a lamp is possible, however this heats up the watch and this may reduce battery life.
If you need to know more about the Eco Drive, look for detail tech manuals for all types here: http://www.citizenwatch.com/downloads/tech/tech.htm
Those are great watches as long as you remember it needs light to charge.

A "non" fully charged watch will sometimes "jump" seconds rather than indicate one second intervals. Charging these small solar panel watches takes forever, in BRIGHT sun. Have you tried leaving it outside, in the sunlight, for at least 12 hours?

I have a similar solar modle Ive had since 1995 , about 4 years ago it started loosing time and the second hand started double ticking. I sat it down out side on a cool summer day for the hole day in the bright sun and never have had a problem since. knock on wood! It was also runover by a car last year and still works good. I wont ever get ride of it. Hopefully this helps u guys out