Permanent Resident Wanting to visit U.S. after Many Years Abroad

[ImmLawPlsHlp]

My mother became a U.S. permanent resident when as a U.S. citizen I petitioned for her. Since then she returned to her home country and remained there for many years. Her permanent resident card has since expired.
She would like to visit us in the U.S. now. What her are options?
- Is it possible to get her permanent residence reinstated? If so, what would be the process?
-Could she apply for a visit visa? If yes, does she have to take any specific steps to formally abandon her permanent residence before she can apply for a visit visa? Or, is her permanent residence now considered already abandoned, and she can directly proceed to applying for a visit visa?
Would very much appreciate any guidance. Thank you.

[JoeF]

A permanent resident has to live in the US.

She can't get a visitor visa because she has shown immigration intent. Her best bet is to file form N-407, Record of Abandonment of Permanent Residency, and then file for a visitor visa.