The most common reason for tassel dry up and no cobs is drought during the critical silk stage, when the silk-like tassels are just forming. However there are pests that can also cause this, including corn borer, aphid, and mites. If you see no sign of pests, it could be lack of water. Corn needs at least 1 inch of water a week when developing, and more when the temps are above 90 degrees. Don't give up next year. Just add a few inches of organic matter to the soil to help it to hold more moisture. Keep growing, Marianne Binetti