My father passed away in 1974. His will lift his Louisiana real estate to his spouse and two adult children. The real estate was sold without the knowledge or consent of one child.
What recourse does that child have?

First, please don't piggy back your questions on someone else's thread. I've moved your question to its own thread.

Was the property ever transferred to the heirs? Seems a long time to keep the estate functioning. If the property was transferred without his signature the sale may be voided. The child should consult an attorney.