Loud noise when cranking engine

Just wanting your input and advice on common mistakes. I have a fairly grand knowledge of what all I am surely putting on the priorities list... clean engine. Replace valve gasket(again),[ this time though] replace spark plugs. Check and tend to their cylinders. Along with checking and replacing my crank and can sensors... pretty sure the guy who slammed on brakes(I'm just going to believe he didn't mean to and had Parkinson's) after leaving the stop sign wasn't a huge help here. No matter, it's obvious i had problems before that week. The sludge in the back of the bay is despicable and i am ashamed i trusted any one to conduct my engines care for any time period. I know I drained the battery on accident today but to crank it sounds like I put a busy shipyard in my hood. Just makes me sick.