I'm having a problem with my 03 Chevy Cavalier,The engine was ran with very little oil in it and it started making a "helicopter noise" The serpentine belt seems to be loose and i can hear it slapping(Thinking this is the helicopter noise), but the oil is also kind of sludgy and there's a knock. What can be done? Is my engine toast?
I'm attaching a picture of what the oil looked like prior to adding new oil.

 

Wowsers.

How long did it run without oil?

That looks like coolant or water mixed with the oil.

Is there an automatic belt tensioner on this model?

What does the knock sound like? a stone flopping around occasionally from down below? Probably rod bearing.

 

Well a friend of mine was driving it for a while and i knew it needed an oil change so it rode for a while with little oil in it....

I think there is an auto belt tensioner.

the knock mostly sounds like the broken belt slapping but it also kinda has a pebble noise yeah. Is that extremely bad?

 

the timing chain tensioner is oil pressure assisted. Have a professional assess it. Hard to do accurately do that over the net even with a video.

 

What tech2 said.
I used to own a repair shop in Europe, before I moved to warmer climate. Here's the typical scenario (the engines are pretty much the same on both sides of Atlantic):
It starts with low coolant, results in warped head.
Then oil and coolant get mixed because of blown head gasket (warped head!).
At this point lubrication is not adequate any more because the oil is contaminated.
All above results in enormous wear and tear with all kind of disastrous consequences.
Just to start the listing:
Cracked cylinder block head;
damaged crankshaft and bearings;
damaged camshaft bearings;
etc, etc ... keep going.