Oil pressure an rattling an knocking sounds

Well you have no oil pressure causing the engine noises. Check the oil level first to see if there is oil in the engine, and if there is then check the oil pressure with a mechanical gauge. If there is no oil pressure then either the oil pump is not working, (not likely) or the main bearings are bad on the crankshaft. All lower end bearings would need to be replaced, but, may as well do a rebuild or find another engine.