Are they newly planted ones?

And I'd ask, in addition to Steragram's query, are they in pots or in the ground, and which leaves - just at the bottom, or all over? And which laurel - bay laurel, spotted laurel or cherry laurel?

Yes they are newly planted

Leaf drop is due to environmental stress. Something drastic has changed. This typically happens when a plant is moved indoors. Will it recover? It can but that depends on it's new growing environment.

It could be possibly the result of root damage or perhaps planting into ground that was too wet - soil can set like concrete if its disturbed then. It certainly won't be water shortage at present! Not a lot you can do at this stage but wait and see.
Answer Bamboo's questions too - she is very knowledgeable.

Most of the forms of Laurel will resprout quite easily, as long as the stems remain fairly healthy. So, where there is life, there is hope. Just remember that it may take longer days and/or warmer weather to see new growth.