Hi,
First, you need to check the oil pressure sending unit. It should be located just above the oil filter at the engine block. If the wiring is frayed or exposed it may be shorting out causing the light to come on. Also, have the sending unit checked for proper operation.
If sending unit is ok, then there is a possibility that the oil pump was damaged from running engine with low or no oil. If the pump is damaged it will need to be replaced. If you have a knocking or clacking noise, then you will be looking at an engine rebuild or replacement due to engine bearings being damaged.
IF there is no noise, then you should only be looking at either the oil pressure sending unit or oil pump. If oil pump is bad and you dont have it repaired soon, then you chance damaging the engine due to insuffecient oil reaching the cylinder head.
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