It will help to have more information. Do your parents live with you or at home? What is the condition of their health? Do they have dementia or Alzheimer's?
The issue of elders who were once reasonably clean adults refusing to take showers and wear fresh clothes is one that is far more common than most people think. Sometimes the issues is more severe than just refusing a shower. A checkup with a doctor is a good idea.
Here is an article that will give you some insight on your elder care issue. My Parent Won’t Shower or Change Clothes. What Should I Do?
The issue of elders who were once reasonably clean adults refusing to take showers and wear fresh clothes is one that is far more common than most people think. Sometimes the issues is more severe than just refusing a shower. A checkup with a doctor is a good idea.
Here is an article that will give you some insight on your elder care issue.
My Parent Won’t Shower or Change Clothes. What Should I Do?
https://www.agingcare.com/articles/elderly-parents-who-wont-shower-or-change-clothes-133877.htm
Good luck.