Not likely to be frost damage - you don't say which laurel it is, either Prunus laurocerasus or Aucuba japonica, but both are hardy anyway. Unless you just mean the new leaves have gone brown and dry -tender new growth might be affected by a sudden sharp frost. If all the plants have dead, brown leaves with no green anywhere, something has caused them to die back, so check for weedkiller damage, infestation or fungal infections.

or enough water ofcourse.just a thaught