laptop will not charge or run on battery?

hi ive had my laptop for 11months and its never had a long battery life but for the past month or so it hasnt been able to come off ac power. the battery say's its 80% charged get its not charging anymore and when the ac lead is disconnected the laptop turns off. the battery has not charged at all for the past month and the laptop switches off as soon as the ac lead is removed do i need a new battery or is it something else?
the laptop is a medion 2030
any ideas novice here