how can i fix starting fault on 2004 citreon xsara?

Having had no problem with starting the car before, I left the car over night only to find it would not start this morning. All the dash lights, main lights and electric windows work fine, but it seems that there is not enough power to turn the engine. The battery is the sealed type and the sight glass shows green. The car will however start from jump leads or a bump off. I hope someone can help, thanks Terry