as you say you are in a very good reception area, I would think it fair to presume that your lack of signal may well be down to a local area fault or maintenance.
For an update on work or maintenance being carried out in your area you could give Virgin mobile customer services a call on 789 from a Virgin mobile or 0345 6000 789 from any other phone, advise them of the problem & see if they can offer you a time scale for normal service to be resumed.
If you want to say thanks > click 'Kudos'. Answered your question? > click 'Mark as Helpful Answer' also.