It is most likely that your plant died from no water reaching the roots. Very often we do not give a plant enough water generally because we do not want to overwater, so we water,and when the surface is moist and the plant looks watered, what we have given has not reached the roots.
The darn it of it all is that rosemary just suddenly goes brown (it doesn't wilt like other plants might). Is this what happened with your plant?
I am not sure that you can rescue anything but try by snapping off all the dry bits ... they will snap easily and when you get to a piece that doesn't snap, leave it and snap on as it were.
It will obviously be a very odd shape, but no matter. Then soak the pot in water, (though yours looks too big to do this) so add water cup by cup until the saucer is full of water. Leave the plant with the wet saucer for a morning or so - it will draw up the water it needs. Then empty the water and see what you see.
Keep watering every second day or so, enough to ensure the roots are getting a fair share. DO NOT FEED until you see new growth, and only then use a little liquid fertiliser.
Trim the top after you see the new growth and cross your fingers! Rosemary is a pretty tough customer and may respond, I think it is worth the effort but do not be disappointed if it does not work out as it may have gone too far already.
Rosemary thrives in full sun but when in hospital, as yours will be, dappled shade and no direct sunlight is best. When you see new growth, gradually give it more sunshine until it gets to its original placement.
If your pot is too big to move, then think of a way to 'dapple' the sun - use a screen of sorts etc. DO NOT disturb the roots at all by being tempted to repot what you have left into a smaller pot. Use a natural mulch to pretty up the pot while it's in rescue mode!
Good luck and I say cheers
Edited by Lestie - ContainerGardens (12/02/12 08:47 PM)
Lestie Mulholland - Container Gardening EditorContainer Gardening Site Container Gardening Forum"Things GARDENING are great ... they are my daily smiles on toast!" - Jennifer St John-Rose, formerly black thumb recently turned green.