Do you have to file taxes even if you didn't make money? What if you had no profit and no loss? What if you had revenue but your expenses exceeded your revenue? I'm asking about both federal and state tax law.
You're essentially asking the very common "Do I Need to File a Tax Return?" question. It's common enough that the IRS answers it right at the beginning of the Form 1040 Instructions, and it's answered fairly thoroughly here:
There's about 20 questions in that checklist which are mostly pretty specialized, but assuming you didn't have taxes withheld that you'd like to get back, and didn't have any retirement income/disbursements this year, the only interesting question is this:
"Were you self-employed with earnings of more than $400.00?"
Sounds like your losses outweighed your profits, and assuming you had no other income, I'd say you're fine not filing.
Can't really speak to state law since that can vary so much, but your state's laws are likely similar to federal, and you can probably find a very similar answer near the beginning of the instructions of your state's income tax form.
If you're "living off the land" and make no money, then you don't have to file. Though you might be able to actually make money through credits and the like if you do file.
If you've lost more than you've made, then you'll probably need to file since someone will have needed to report that they paid you (W-2 or 1099-MISC). If the IRS receives a form saying that you made X and you don't file, they aren't going to just take your word for it that you lost more than you made, right? That, and if you want a refund, you'll almost certainly need to file to get it.