Is something actually wrong in my head?

Here's the situation, I can't cry. I haven't cried since i was about 10, and am now 18. I am not depressed and am honestly concerned why i can't cry, a close friend posted a week ago that they'd kill themselves on facebook. I feel like an asshole because all i felt was shock, called my other friends to help him, and felt no need to cry, I honestly think i have a mental disability. I still feel sadness, but i just can't cry no matter the situation. I am happy with my life but whenever i get bad news my instinct is to shrug it off and carry on, or if something really bad happens i feel sadness but can't cry. Can somebody let me know if there ARE some mental disabilities that cause this?
Is something actually wrong in my head?
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