Clicking under bonnet and not starting

i tried startin my car few wks ago and it wouldnt start then realised it had run dry of oil,put sum in it was runnin ok after a jump start but now stopped workin again and all i get is a clicking noise from under the bonnet.the car has not had oil change or any sort of service 4 over 4 yrs but i am doing that as soon as i find wot is the reason why it not startingas i am desperate 4 my car 2 be 100%.many thx