What I should I do if a job change their policy after almost five years?

ny name is Dorothy and I have been employed by this company for 4 years 9 months and was offer flexible scheduling when I was hired. Now due to changes in the company they no longer have flexible schedule, and there pretty much forcing into a different program for sales ( which my job will depends on, if I dont sales I can be fired) and I am a terrible saler which is why I didnt apply for that position or resigned from the company. i'm not sure what to. i am located in FL. Please help