My laptop shuts down when i remove d adopter.plzzzzzzz helpppp!!?

hi...okey so ,,,i ve got ADVENT 7073 laptop...it about 3 yrs old,,d prob is that my laptop seems to be fully charged,,meanz d icon on d screen shows that d laptop is 100% charged but at d same time it makes beeping noise like if its not charged but when i connect it with the AC adopter it stops beeping....so my laptop only works when its Connected with d AC adopter....and when i remove the AC adopter it starts beeping again.. plllz help....