Homelite Textron XL automatic won't start?

My chainsaw 50157 (23"bar) was serviced 3 years ago & used once afterwards.Now it won't run-no spark.A fresh plug makes no difference.Where do I go now?Are there any common faults with this model?Is it likely to be a u/s coil,points or what?Can anyone suggest how old it is and where might I get a manual for it?Its in excellent order otherwise & hasn't done much work.Thanks in anticipation.Dave.U.K.