Voluntary Dismissal of Suit

Hello,

Quick overview of the procedure thus far:

Suit filed in state court (TX)
Def. files counterclaim
Plaintiff voluntarily dismisses suit.
No further action by either party
Plaintiff re-files suit


What happens to Def. counterclaim? Do Def. attorney's have a legal responsibility to continue with their counterclaim? Now, the Plaintiffs have filed the same suit, but Def. attorneys did not proceed with their counterclaim and they advised Def. that no further action was necessary. Def. attorneys did not file a summary judgment in Def. favor.

May the Def. file a claim in District Court-Texas against his attorneys for legal malpractice?