Plugged in , not charging Error

Hello,
I have an acer aspire 5732z and from some days I have been getting this problem in my laptop . please help me with this problem . Have my battery expired ? One year has passed since I bought the laptop . I am really worried . please help me . it shows : 8% plugged in , not charging . I have tried unistalling the driver and all but still does not work . I have Windows 7 ultimate