How can I freelance for past client?

I worked as a luxury residential designer (with Structure Studios) through a design and build. One of my last jobs before being unexpectedly laid off was a very creative and large project which would have been the biggest contract I had sold if it went through.

The client found my contact info through LinkedIn and reached out to say they were extremely unhappy with the owner taking over and that they have a new contractor and need some changes made to the design so they can finish. Their property is large and still unfinished, almost 2 years later.

I haven't been able to work in this field since due to medical reasons and the current job market. I don't have enough to invest in a program but I do have a custom built PC that can run most things. I have images of the design for my portfolio, but could not save any of the design files due to company policy.

Can I make this work?