New Blooms On Purple Phlox Are All White

Q: For a year I have had a beautiful row of light purple phlox in my garden. Today I was shocked to see that the new blooms sprouting on the plants are all white. What happened ? can I change them back to light purple for next year?

A: My guess is they have reverted to their original parentage. I'd start shopping for new plants. Best And Happy Yardening, Nancy.