I have a blown engine and a cracked cylinder. Is it worth fixing?
At the minimum you would need a new/rebuilt short block. What’s the condition of the rest of the car? Transmission condition? This is a financial decision only you can make.
Blown and/or cracked means a new engine. So why do you think that it is blown and has a cracked cylinder? A cracked cylinder is near impossible to diagnose without tearing the engine down or by using a Borescope.
Cracked cylinder head?
either way, it sounds like it’s time for a replacement engine, a good used engine would make the most sense
That is for you to decide. Can you get a new engine for 4 grand or so? Can you afford it?
I guess it’s mostly math. What would it be worth in good condition? Maybe $3-5000 tops? Right now it would be maybe $500 junk value without an engine. So you can price an engine and if it can be done for maybe $2000 and then you plan to either trade or drive it for a while it can make some sense. Otherwise why bother and just trade now before sticking any money in it. You really need to like the car though to put that kind of money into it.