Old movie I can't find

When I was little I saw a movie about a boy that stopped aging. If I remember correctly he had an accident and he stayed young boy for decades and the movie follows his life. In the end he fell down the stairs(?) and started growing up immediately. The movie is an older one made before 2000 or just around 2000. Can’t remember too well as I was so young. Any help is appreciated!

This movie is not that old and it is a woman who is not ageing:

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This is also probably not the right one, in this one the man ages backwards:

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It is „Die Blechtrommel“