Hi, thanks for posting your query to us.
The information you have provided too brief and inadequate to reach a diagnosis.
However, the changes in the toe nail you have mentioned are most commonly due to toe nail infection
, most commonly it is due to fungal infection
Nail matrix is responsible for the nail formation. As long as the nail matrix is not involved these changes are reversible. The infection has to be treated appropriately. You have not mentioned about the treatment taken and for how long this has been present. Whether there is associated pain and discomfort?
I suggest you to consult a dermatologist
for proper examination and treatment of the condition.
Hope this helps you.