Q: My frustration is that I was working with a headhunter. I have found out that headhunter left the firm without telling me. So I left a message for another headhunter so maybe she may help me find a new job and she never called me back. Should I try to find another agency? And how do I start with networking during tough job market?
A: It is an exasperating experience when you are working with a placement professional ("headhunter") and they leave the firm without notifying you. However, we don't know why your contact left the firm. Perhaps the individual did not leave voluntarily and was not permitted to contact you about their departure. Or, as you suggest, the individual left the company, and somewhat unprofessionally, did not share this information with you.
You can certainly consider working with another agency, assuming you did not sign any exclusive agreement with the prior agency. Placement agencies are often helpful especially if you have a specialized skill. Many employers will use placement agencies if they don't have the in-house resources to devote to a search for talent or the skill set is hard to find.
Relying solely on an employment agency is risky though. An employment agency will try to place you if they can earn a fee. Some agencies will not work with you if your skill set is not in demand.
As you probably know, networking is critical to any job search. Establish a networking goal. As an example, connect or re-connect with 10 colleagues in a single week. Remember it is not just the individual with whom you are meeting, but instead their entire network of contacts. Offer to pay for coffee or an iced tea. Some meetings will end without immediate success. Some meetings may be fruitful and connect you to opportunities.
Check job boards too but don't spend more than 25% of your time checking job boards. Some job seekers, especially introverts, will spend their entire work week online without meeting a new contact in person.
Join LinkedIn if you haven't. Begin connecting with others on LinkedIn. Join groups on LinkedIn and watch what others are sharing. Check out the Jobs tab on LinkedIn and search for roles that might be appropriate for your skill set.