As far as I understand you had a green card but did not live in the U.S.
Because you did not establish a domicile in the United States the green card was abandoned. Under immigration law a legal permanent resident has to establish residence in the U.S. and must not abandon it. Here it sounds as if you never established residency.
Once a petitioner has abandoned his green card there usually is no way to get it back. You would have to qualify new, that means you will be treated as if you never had one.
What aggravates things is, if you had a green card and abandoned it and now seek admittance as a visitor, admission can be denied because of the possibility that now you want to stay in the U.S.
This is a situation in which you best consult an immigration attorney.