What can she do if she committed a felony such as petty larceny, showed up for the court date but never paid and now she has a warrant?

Petty Larceny is a misdemeanor. She can hire an attorney to lift the warrant for her, or she can turn herself in to police, pay the bond, and they will release her and give her a new court date. Then she can pay the fine or go to court and ask judge to put her on a payment plan.