They are sub tropical plants with very tough leathery leaves, so the sun cannot be the problem. If you could post a photo it might help to see what the damage is like, but as long as there are healthy green leaves growing, it is usual for the old ones to go brown and die off. Cut them off with scissors or a sharp knife for cosmetic purposes.
They like dryish conditions so if your plants are severely damaged it could be over watering or being frosted. More information would help, for example how large are they and in what size pot.

thanks this is what they looked like a month ago they have never been over watered and i think they in quite big pots well i hope they are ? also i have a Strelitzia reed that has gone the same way i keep them in the bathroom where its very warm all the time i hope i can save them i have put pictures in my profile as i dont know where else to put them many thanks

Just seen your photos. I'd say that these are vastly overpotted. So the roots may well have rotted. Strelitzia like very dry conditions and like their roots to be restricted. I'll send you a photo of ours tomorrow if I can, and you can see how big they get in a smallish pot. You won't get them to flower until they are a large plant and our first one took about three years. Sorry to be pessimistic.

Forgot to say also that they like lots of sunshine and bright light. I don't think the bathroom is the best place for them. If some of them are still growing with green leaves try to put them in a very light, bright spot with plenty of warmth and keep watering to a minimum. I've hardly given ours a drop of water all winter until recently and it is fine.

thanks ii will repot them into a smaller pot i hope i can save them

Good luck and I hope they survive. Ours has just begun to open its flowers, much later than usual, after a winter in the unheated but well insulated conservatory. I like Strelitzias very much as the flower shape is so different and they last so long.