why do threads disappear? (..and come back months later?)

dear moderators,
dear boardmates,
do you know why some threads vanished for several months and all of a sudden came back in full size?

i started the pic and clip thread, because the photo and the movie thread were lost..

now they are back..

anyway,
greetings from a sunny sunday afternoon,
thanks to all posters and of course the femaledom crew.

_bleep