More details are required.
Firstly, the cause of issue (white patch) needs to be identified. What caused it? How was it triggered? How long back it was noticed (duration of first observation?)
For temporary solution, moisturiser can be applied
But again, more detailed information about this patch is required for better treatment
Next Steps
Connect with me on Practo for better treatment
Health Tips
Avoid self medication as it can be dangerous and becomes more complex to provide good treatment.