If it's been in that position for a long time, with any light always coming from the same direction, that would explain this. It should have been rotated regularly, say bi weekly or monthly, but the only thing you can do now is to turn it so that all the growth is pointing away from the window, and leave it in that position for some months. It may, or may not, persuade the existing growth to change position, but I have to say that isn't terribly likely, so keep an eye on how it's growing - if it doesn't become more upright, but new growth starts reaching for the window, you'll have to turn it regularly to keep that upright and not worry about the bent growth you've already got.
Over time, with new growth, you may want to consider cutting out this bent growth, but see how it goes.