If the plaintiffs never responded to your lawyer's counterclaim, your lawyer should have taken their default to end their ability to defend themselves, meaning, you win.
If the plainitffs dismissed their complaint "without prejudice," that means you can bring the same lawsuit against the same defendants again. What limits the right to do that is whether or the time limit in which to file, the statute of limitation, has expired. If the plaintiffs dismissed their complaint with prejudice, then they cannot file it again, it's over forever, you win.
Since you have a lawyer, you should be asking your lawyer for an explanation.
Disclaimer: Please note that this answer does not constitute legal advice, and should not be relied on, since each state has different laws, each situation is fact specific, and it is impossible to evaluate a legal problem without a comprehensive consultation and review of all the facts and documents at issue. This answer does not create an attorney-client relationship.
If your attorney filed a counterclaim, the other side must respond. If they did not, your attorney should have moved in court for a default judgment. If he falls asleep on the job, the court isn't going to hold his hand.
In Illinois, you can voluntarily dismiss a case and have one year to re-file it. So a plaintiff can drop a case (so long as it's a voluntary dismissal) and bring the same case again, but not three years later.