Lost all oil pressure

well here we go again this 2,0 abf.  Starting be a pig car was perfect oil pressure Happy fitted pressure gauge 2 days ago as I say pressure was good 3 idle 6/7 with revs before I switched car off to was old dirt off engine oil pressure was good stated above restarted car up after dry out dizzy cap oil light on. Thought strange  looked at gauge nothing thought or I blasted wire off had look no all wires on perfect removed wire off switch light goes out so thought right take switch out start up guess what nothing no oil damm damm is they any thing common on these before I pull sump off look at pump 

Changed oil and filter
Fixed its self oil was good still golden which came out
6 bar pressure on idle now 8bar on revs
😆