Please grant me one dumb question

[thekubiaks]

I am fairly fluent using Hashcat with all of the different algorithms when a hash is present.  My question (after much searching) is how do I attack a simple text file that has been encrypted with something like blowfish or even one of the many listed hashcat algorithms when no hash is evident?   In other words if all I have is a small encrypted file, how do I proceed??  Thanks