Jonah 2:1-2 Now the word of the Lord came to Jonah the second time, saying, "Arise, go to Nineveh, that great city, and preach to it the message that I tell you."
A "second time." Jonah's repentance gave him a second chance to obey the Lord and to fulfill his ministry. And he did it successfully. The apostle Paul tells us that "the gifts and calling of God are irrevocable" [Romans 11:29]. Jonah's disobedience did not take away his calling as a prophet. The discipline of the Lord was fruitful in his life. But compare King Saul. He also got a second chance after failing to wait for Samuel [1 Samuel 13] and he disobeyed again, and lost his kingship [1 Samuel 15]. But even that took many years to transpire after David was anointed.
We are often taught, "Our God is a God of second chances." And He is. Our failures in ministry do not automatically disqualify us, for the Lord is patient with us and He knows our weaknesses and predilection to sin, and He knows we are always on a learning curve. But He does expect us to learn from our mistakes, and honestly repent from our failures.
Now there are examples in scripture where sin and failure to obey brought immediate irrevocable judgment with no second chance: witness Ananias and Sapphira, or Lot's wife. So we ought to take notice that there are critical moments, decisions, and situations when our disobedience won't be tolerated with patience. Thank God they are probably rare, for He is amazingly patient.
You may have failed the Lord in your service to Him through some character flaw or hidden sinful attitude which has been brought to light. Repent, and get back in fellowship with Him. And watch that you don't make the same mistake or worse. He will restore your ministry because He loves you and has called you; and will probably use your failure to make you even more effective. Our God is so wonderful.