thanks for all your suggestions.. i tried cleaning with vinegar+detergent and glass cleaner, but it was useless.
The thing JALA or contaminant or sludge are the deposits on screen which can be removed with chemicals but scratches cannot. Scratches can be removed with buffing only.
Margallar has has suggested clay bar and that can be a good thing to try but my problem is not scratches it only the sludge.