YOU SAID:

my nans fallen down the stairs

INTO JAPANESE

私のナンズは階段から落ちました

BACK INTO ENGLISH

my nans fell down the stairs

INTO JAPANESE

私のナンは階段から落ちた

BACK INTO ENGLISH

my naan fell down the stairs

INTO JAPANESE

私のナンが階段から落ちた

BACK INTO ENGLISH

my naan fell down the stairs