A permanent resident (called lawful permanent resident or LPR) or conditional resident (CR) who has remained outside the United States for longer than one year, or beyond the validity period of a re-entry permit, will require a new immigrant visa to enter the United States and resume permanent residence. A provision exists under U.S. visa law for the issuance of a returning resident special immigrant visa to an LPR who remained outside the United States due to circumstances beyond his/her control.
If you are an LPR unable to return to the United States within the permitted time due to circumstances beyond your control (e.g. medical incapacitation or hospitalization), you may apply at the nearest U.S. Embassy or Consulate for a Returning Resident (SB-1) immigrant visa by completing a DS-117 and paying a fee of $180. If your DS-117 application for returning resident status is approved, you will be required to obtain a new medical examination at your expense and submit a new DS-260 application for a visa and pay the required fee of $325. If the DS-117 is denied, then your only recourse is to have your prior petitioner refile with USCIS for your immigration benefit.
For more information please visit https://travel.state.gov/content/visas/en/immigrate/returning-residents.html or make a notarial appointment to pay the $180 fee and file a DS-117.