If its a frost free freezer it is probably frozen up, something you cant see but if you turn it off for a couple of days it will defrost itself, their is a small fan that blows cold air up to the fridge if it is frosted up it restricts air flow (common fault with frost free fridge freezers) and the fridge warms up, give it a try before you go out and buy a new one. It is usally caused by fridge or freezer door not being shut properly and makes the freezer work to hard.
Hope this helps
Gordon
February 2010