Grass is turning black and dying

My lawn is turning black in large patches and almost apprears burnt. I put some sand and fertiliser on early last summer in may. But since september black patches have appeared and the grass dies. The patches dont appear to be like the fungal pictures I've seen. I've reseeded some of the areas but its not taking too well. Can you help?

 

without further info, i have to assume some sort of black mould.......if so, rake vigorously wih a spring tine rake, aerate with fork to improve drainage, re seed when temperature is higher.... you soil needs to be 5 degrees C