I might ask, how large did the leaves get before they yellowed/withered? One indication of poor soil would be poor growth. Melons have various pest problems, aphids, spidermites...just suggestions, as I haven't grown lot's of them but I'm familiar with some of the pest issues. Also, they have moderate water requirements,
I agree with cricket, more information would be a great help.
NEVER add fertilizer without some extra information, fert.s can be a cause of damage as much as pests or disease, and soil is the key many times.