Just because you have failed miserably at something the first time does not mean that you are not called to it. God may have let you fail, so that you may rely on Him rather than on yourself. 
Moses’s story is retold in the book of Acts through Stephen. He says that Moses wanted to rescue his people from slavery and attempted to save them. However, he failed miserably and fled to desert to lick his wound. (Acts 7:27)
After 40 years (that’s a long time to wait!), God calls Moses to the same task that he originally failed at. Moses was sure that he wasn’t the right man for the job. After all, he tried many years ago and failed. But it was through his own learning and strength. He might have thought that with his credentials, he could’ve convinced Pharaoh to let the Israelites go. But he was seriously mistaken. It would take nothing short of God’s right hand to deliver the Israelites from the hands of the Egyptians. 
So, if you attempted something, thinking that it would serve God and humanity but failed miserably, know that God may call you to it again. But not before He humbles you completely so that you know it’s not your wisdom or strength, but God’s.

PH