Are they in pots or in the ground, Maryalger?

I'd ask why you've used the term 'trees' - are they standards, in other words, a straight stem with all the growth at the top?

I am a very novice gardener and the lavender is in a pot. It does have a straight stem with all the growth at the top which resembles a tree. As i mentioned the leaves have begun to bend over and look like they are wilting.

Okay. I assume the plants are outside - has it been very, very cold with you during the last couple of weeks? Is the compost in the pots wet or very dry? If very dry, give some water. Otherwise,just wait - the topgrowth may be drooping just from the cold previously, but the worst might be that the compost froze solid for too long. Nothing you can do but wait - and clip over lightly in March if they survive to reshape them.

Thankyou for that. It has been cold recently, do you think it would help to feed it with blood and bone meal or can you suggest what kind of plant food to use.

Nope, too early to feed them, that should wait till the growing season starts, so around March - late March if you're in the North. Blood, fish and bone will do, or Vitax Q4. Check whether they need repotting at the same time - if you've had them more than year, they may be potbound.

Once again thankyou for your help, i'm sure i will be a frequent visitor to this site.