If you remained outside the US for 1 year or more, without a Reentry Permit allowing you to do so, you have in effect "abandoned" your LPR status in the US. There isn't much you can do, except ask the same parent or relative that originally sponsored you to petition you again. If it is through the DV Lottery that you obtained your LPR status, then you are out of luck. If it was employment based, then you are out of luck again, unless the same (or different) employer wants to sponsor you all over again.
Behar Intl. Counsel 619.234.5962 Kindly be advised that the answer above is only general in nature cannot be construed as legal advice, given that not enough facts are known. It is your responsibility to retain a lawyer to analyze the facts specific to your particular situation in order to give you specific advice. Specific answers will require cognizance of all pertinent facts about your case. Any answers offered on Avvo are of a general nature only, and are not meant to create an attorney-client relationship.
Your residency has not be voluntarily surrendered unless you have been outside the USA for I year. It sounds like you have not been gone for over a year so you are technically still an LPR. I suggest you go to the us Consulate ASAP and explain the situation. You may be able to get a stamp in your passport to indicate that you are an LPR and/or file for a renewal card.
I'm not sure exactly how long you remained outside the US? I highly recommend you retain an immigration attorney to help you. If you were outside the US more than one year, your residency is considered abandoned.