Hi Inicholson,
That's a good age for a yucca, why its suddenly bent over I'm not sure but it sounds to me rather like its grown too fast to support itself, could be a cobination of over-feeding, too much heat, or lack of light or just one of those things ?
The good news is, Yuccas sprout very readily if you cut them back into old mature wood, I've known them to reach the cieling hieght and seen them cut back hard and they will eventually sprout lower down the stem.
If you try this it's best to saw it down to somewhere where you would like it to sprout from, (but I would'nt cut it back any lower than a foot) dress the cut ends with some kitchen tisue and secure it with an elastic band and 'touch-wood' it should sprout a bit lower down, any long stubb can be cut back further at a later date. Good Luck Tbird+