It is unclear by your question, exactly what your situation is. If you have been outside the U.S. over a year and did not apply for a re-entry permit, set up your life and home in Mexico for even less than a year-you may have abandoned your residency. If so, you appear to be applying for a new immigrant visa (unclear). If your "nenewal appointment" is an application based on your marriage which is no longer viable or existant, you cannot seek a visa based on that marriage. I would consult with an immigration attorney right away. We are available if you wish to contact us and may be able to help. Law Offices of Sean Lewis 615.646.6002.
I'm unsure why your were "sent" to Mexico. As well, it is unclear why you are in Mexico for a renewal of a green card. I'd suggest you retain a lawyer and fully discuss this matter with him/her.
I agree with my colleagues.
(213) 394-4554 x0 Mr. Shusterman is a former INS Trial Attorney (1976-82) with over 35 years of immigration experience. His response to your question is general in nature, as not all the facts are known to him. You should retain an attorney experienced in immigration law to review all the facts in your case in order to receive advice specific to your case. Mr. Shusterman's statement above does not create an attorney/client relationship.