Photophobic Cactus

I have a long, tall cactus which has suddenly decided that it doesn't like light and is doing all it can to avoid it.

It is currently leaning at 90 degrees and curving like a hook.

Anyone know a way out of this, I've tried everything I can think of so far?

 

Is it definitely a catus and not another succulent?...the base is not rotting is it? most cacti are desert plants and so enjoy full sun, except the epiphyllums and jungle cacti

you could always lop the top off an re root it

 

yes, take a scalpel or very sharp blade and make as clean a cut as possible near the base of the plant... leave the parent plant in place, as very often new growth will appear... take the cutting and face the cut end to the sun... leave it to dry out COMPLETELY, then lay it on top of some sharp sand which is a few millimetres thick, and lying on top of compost... add just a touch of water, and it should root itself again...