how to re-obtain green card which already returned to US Embassy volunteerly

[guynew28]

My parents got their green card 16 years ago, but they returned their green card to foreign US Embassy volunteerly 10 years ago because they believed they were not able to stay in USA at least 6 months in a year due to their business.
When they returned the green card to the officer at the US Embassy, they were told that they can always get their green card back in the future with the green card returned receipt.
Now they are ready to stay in USA for long term. What will be the procedure to re-obtain their green card.
Should I fill (I am US Citizen) I-130 for them or there is a quicker method?

Thanks

PS. Under the thread named "GC for Parents - AOS and CP - Information Source".
It said :
Where to File - Concurrent Filing - I-130, I-485, I-131, I-765 - AOS
Chicago Lockbox
U.S. Citizenship and Immigration Services
P.O. Box 805887
Chicago, IL 60680-4120

What if I already filed the I-130 to Vernon Center 2 months ago, is it too late to file the rest of the form concurrently?
If not, shall I submit the rest of the form to Chicago or Vernon Center?

[boatbod]

When they returned the green card to the officer at the US Embassy, they were told that they can always get their green card back in the future with the green card returned receipt.

Uh really? Never heard that before.

Somehow I suspect the situation is really not that easy. Once you give up your GC and abandon your US residency, the only way to get it back is start over. Hopefully either you or a sibling is a USC, as thats likely to be the only way to begin sponsoring them for an I-130.

[PraetorianXI]

Also you can only file the forms concurrently (i-485) if they are present in the united states. You will have to wait until the I-130 is approved now and go through consular processing.