Laptop Charger?

Hi, yday my laptop wud not charge and i told my da, he said he had a spare charger to try it, i did an it was working perfectly all day, in the last half hour it says the battery is not charging even to=ho switched on and plugged in, altho strangly the battery level does not seem to be getting lower, i let my da have charger i was using yday and its not working on his, i assumed that was the problem until this.