Since you're out of my area there are probably things in your MLS that are different from mine. I suggest you reach out to either the remaining agents managing broker or cancel everything and start over.
If you've been listed for a while and it's not selling, something has to change. Sometimes it's the marketing, the pictures, the accessibility or the price. If you aren't well marketed, no one will find you. If you don't look good online and on the flyers, no one will seek you out. If they seek you out, but can't get in due to limited access for showings, you won't get any offers. If your not priced competitively then buyers will just make other choices. The best pricing strategy is to be a great value compared to your competition. In many areas a low price brings multiple offers and the price goes up.
It's impossible for me to know why you haven't sold, but if you are not under contract with an agent. Get some fresh opinions and interview some new ones to see what they suggest.
I'm not sure about your question, so I'll make some assumptions and go from there. You are a seller and have an agent that listed your home. You mention it was co-brokered, so that indicates more than one agent.
Listings in most states actually belong to the managing broker and are serviced by the agent who originated them. If you lost an agent, the office and managing broker would still be responsible for taking care of you. The co-broker may step in or the managing broker may appoint someone else. What you need to do is talk to the managing broker for the best answer. If you call the office phone number for your previous agent and ask for the managing broker you should get a better idea of what's going on.
If you don't mind, when you do find out, let us know. I'm always curious of how things turn out. If I've made the wrong assumptions, let us know more details so we can be more help.