What do you mean by "recognize the voice of the Shepherd"? Do you mean you can't read and understand the Bible? 'Cause it's in the Bible that the voice of the Shepherd is heard, not in your head. The Bible is called the word of God for a good reason. It is in Scripture, in the Bible, that God reveals Himself to us and speaks to us of His will, His truth, His wisdom, His commands and of our relationship to Him. So it is that the apostle Paul wrote,
2 Timothy 3:16-17
16 All Scripture is given by inspiration of God, and is profitable for doctrine, for reproof, for correction, for instruction in righteousness:
17 That the man of God may be perfect, thoroughly equipped unto all good works.
The Bible is entirely sufficient to instruct you in all God wants you to know about Him, about yourself, and about your relationship to Him. The Bible is God's "voice" to you; it is the "voice of the Shepherd." If you are God's child, you have no need of a divine voice in your head that can be so easily confused with your own thoughts, or the counterfeit thoughts of the devil. You have been "thoroughly equipped" with Scripture to instruct, inform, correct, illuminate and guide you. Listen to it. Obey it.
Please understand that in the Bible whenever God had something He wanted to communicate directly to someone, He never failed to communicate it. He sent His angels for a visit, or set a bush on fire without consuming it, or wrote with a giant hand upon a wall, or opened the earth to swallow the wicked, and so on. If God has something to say to you, you will know it. You won't have to practice "hearing God's voice"; there won't be some special skill you must develop before you can discern what God is saying to you. Thinking that God is a mysterious voice that is difficult to discern is entirely unbiblical and leads quickly to confusion and frustration, foolishness and sin. If you have to wonder if God has spoken to you, then you know that He hasn't.
God's voice is encountered in the Bible. Just remember: Not everything in the Bible is for you specifically. A promise to the Israelites is their promise, not yours; a command to God's Old Testament prophet is a command to the prophet, not to you; a warning of judgment upon a wicked nation is a warning to that nation, not to you. Be careful not to snatch a verse out of its context and claim it for yourself. Far too many Christians do that especially with OT promises God makes to His Chosen People.
Fear of the sort you're experiencing is, at bottom, just a manifestation of pathological self-centeredness. You want to protect yourself from threat, but you see God as a threat you can't avoid. And so you approach Him with the goal of self-preservation and act to appease the threat He appears to you to be, rather than enjoying Him as the loving, faithful, gracious, holy God that He is. But this is always the way of things ultimately with Self. The more you serve Self, the more tyrannical and selfish it becomes and the more unhappy and fearful you will be. There is no way, then, to enjoy God, to experience peaceful, contented fellowship with Him, when Self sits upon the throne of your heart. Self has to go if you really want to experience the abundant life God offers to you in Jesus Christ.
You have not understood that God loves you. Or, if you do understand that He does, you don't truly believe it. Comprehending God's love for you, however, understanding how deeply and incredibly He cares for you and believing it, is the remedy for your fear. "Perfect love casts out fear," the apostle John wrote, "he who fears has not been made perfect in love." When you have settled into the truth of God's awesome love for you, your fear will dissolve. And there is no greater proof of His love for you than in the giving of His Son for your sake. You can trust and love the One who has humbled Himself, suffered, and then died to save you from the deadly, eternal consequences of your sin.
Ephesians 3:17-19
17 ...that you, being rooted and grounded in love,
18 May be able to comprehend with all saints what is the breadth, and length, and depth, and height;
19 And to know the love of Christ, which passes knowledge, that you might be filled with all the fullness of God.
1 John 4:16-19
16 And we have known and believed the love God has for us. God is love; and he who dwells in love, dwells in God, and God in him.
17 Herein is our love made perfect, that we may have boldness in the Day of Judgment; because as He is, so are we in the world.
18 There is no fear in love; but perfect love casts out fear; because fear has torment. He who fears has not been made perfect in love.
19 We love Him because He first loved us.