N’Zogbia joined Aston Villa from Wigan in a £9million deal in the summer. The winger is set to face his former club at Villa Park on Saturday afternoon.
“You can’t replace an important player like Charles. You have got to change the way you play,” said Martinez.
“We are creating more chances but that is down to playing a different way – other players have stepped up and taken the responsibility.
“I am very pleased with that department. We have found the right mixture in our attacking play. We have found the solutions to be an effective unit going forward.”
He added: “We have only been weak because of the changes we have had to make at the back and the suspensions we have had. Once we solve that instability we will se our results improve.”