If you are a US Legal permanent resident or a Conditional resident, you are allowed to travel abroad and stay there for a short period of time. However, if you were absent from the US for more than a year, or stayed more than the time allowed on your Re-entry Permit, you have to get a new immigrant visa to enter the US to continue your permanent residence status. If you are carrying a green card and had to stay abroad because of compelling and unavoidable circumstances beyond your control, you can get a Returning resident special immigrant visa that will allow you to get back to the US. If you cannot return to the US within the two-year validity of a Re-entry Permit, you can still get a return visa. Applications for a returning resident (SB-1) visa has to be filed with the nearest US Embassy or Consulate.
Once your return visa application is approved, it is not necessary for an immigrant visa petition to be filed for you. You have to attend interviews and should be able to establish eligibility for an immigrant visa. Not to forget having a medical examination. There is a fee for both visa processing and for medical test. If you are serving the US Armed Forces or a civilian employee of the US Government staying overseas on official purposes, your spouse and child/ren can use their green card to enter the US even if it has expired. It is not necessary for them to apply for a return visa (SB-1) as long as they have not abandoned their permanent resident status.
You should prove that you were in lawful permanent resident status when you left the US and came out with the intention of returning and have no intention of abandoning your status. You should also have strong evidence that your visit was a temporary one and if the stay abroad was extended, it was only because of inevitable situations not under your control for which you were not responsible.
File a completed Form DS-117 (Application to establish Returning Resident Status) at the US Embassy or Consulate. You will be required to submit your Permanent Resident Card and Re-entry Permit (if available) and other supporting documents. After reviewing your application and supporting documents, the Consular Officer will verify if you meet the criteria reserved for SB-1 status and if he approves, you must qualify for an immigrant visa in all other aspects to get a SB-1 visa.
The US Consulate will give you all details regarding further processing of your SB-1 visa and processing differs from each Embassy or Consulate. If the consular officer finds you have abandoned your residence in the US, it may or may not be possible for you to get a non immigrant visa depending on whether you have established a residence in a foreign country.
Qualifying for a return visa is a bit complicated. If you cannot show convincing evidence of compelling ties abroad, you will be left with the only option of applying for an immigrant visa on the same basis and under the same category through which you entered the US earlier.