How should I go about receiving unpaid wages from an employer?

I have been working freelance for a company for the past 4+ years. I stopped seeing paychecks in March, and was constantly assured that payment is coming, just wait another week. I continued working with these assurances, and in July was told to stop working until further notice. I still have not received payment for work that was completed roughly from February-July. I invoiced every week and typically invoices were acknowledged as received by my supervisor via an email response. The company still is in business-- they're actually calling for applications for new employees! Basically, my question is how do I start going about collecting this back payment? Is there hope of receiving it at all? And if the amount is under 20k, do I have any hope of finding an attorney who will help me with this?