The 66-year-old woman was sitting on the sofa in pyjamas, with the TV listings for the first week of last September still lying open.
Police found the body when they broke down the door of the first floor apartment in Oberursel near Frankfurt last week, the Frankfurter Neue Presse reported.
The building's management had asked the police to break in when the woman's overflowing letterbox had attracted a resident's attention.
It appears the deceased woman had no children, close relatives or friends that she saw regularly so nobody had noticed her absence.