trim it lightly feed with half strength multi purpose feed and keep it watered...it might survive...but lavenders do seem to give up and die sometimes for no obvious reason
i ordered 24 small lavender plants from holland about 6 weeks ago, so far 11 have survived :(
also bought 10 fairly large established potted ones reduced to £1.50 in homebase two weeks ago and one of them looks like it's on its way out.
i wonder if it's something to do with all the rain we've had lately, lavenders like drought conditions.
would guess the fine fibrous feeding roots have rotted.....you could also try uprooting it trimming ang really bad bits and planting it back i a pot wher it will be able to drain better fr a while... improve the soil drainage with some sharp sand before replanting
Mine has been lovely this year .I'm still drying off bunches of it .
http://i35.tinypic.com/w9dv61.jpg
Lavender likes poor soil .If the soil is too heavy and loamy you need to balance it out a bit with grit and sand .Try just chopping it back as far as possible and get rid of any woody growth.
Just chop it back as far as possible ! Don't be frightened to give it a good haircut .
It may recover, if not they are cheap to replace .
I have bought all kinds of Lavender seeds and have had a hell of a job with them - they are so difficult to get to germinate - had I known this I think I would have just bought some plants
When lavenders look as if they are dying they are and they do. Lavendersare fairly easy to grow from cuttings in the spring. Where you have a branch without flowers, break off the small side shoots (about an inch long) that have a cluster of leaves, remove the lower leaves carefully so as to leave 3 or 4 at the tip and plunge it into wet sand just up to the leaves. Use rooting hormone if you have any and put the pot with a dozen or so cuttings in it in a light place out of direct sun. Keep them watered and after a couple of weeks when they have rooted pot them on.