Unsure of what approach to take

[CopperIngot]

I've had this password protected 7z file sitting in my drive for a few years already now, and I have absolutely no idea what method I should use to crack it open. I think it should have between 12 to 14 characters, but that's pretty much it. I could use some help setting up a command that could brute force it without using wordlists.

[marc1n]

If you don't know anything about the password except its length then you are left with the brute force method but in your case recovering a password of 12-14 characters on this 7z hash is virtually impossible. See how many hashes it breaks per second 14 cards 3090 = 14270.2 kH/s Simply put 7z has a very strong encryption algorithm.

[Snoopy]

bruteforcing 12-14 characters will mostly result in a bufferoverflow for hashcat as this keyspace is more than hashcat can store ( 2^64 is max ), so bruteforcing will not work, anyway, if it would work, it would take thousands of years as 7z is a very slow algorithm