Thermopride OL5-85 oil furnace no longer works
Call a licensed oil burner service technician (or a company employing such technicians) and have the furnace inspected, then serviced or replaced. Typically your fuel oil supplier is also an employer of service technicians.

Likely normal servicing is all that is required; this is typically performed on an annual basis, rather than waiting until the furnace no longer works.

This really is not a prime area for DIY.