I went back to Mexico 1n 1996 and never came back to the USA. Now I want to but my green card is expired. What is the best thing for me to do to get legal again?
If you have been outside the US continuously since 1996, you have abandoned your lawful permanent residence in the US and must start the process over. Even if the card were facially valid, your status would have terminated due to the unbroken absence from the United States.
This is general information only; it is not intended as a substitute for legal advice, and does not create an attorney-client relationship.