Who is the speaker of "I find no Peace" by Sir Thomas Wyatt? What is his tone? what are the main themes? What are the figures of speech that used to expressed these themes? How these figures of speech contribute to clarify the themes? What is the mood of the poem in general?

The speaker of the poem "I Find No Peace" is not identified; the narrator speaks about universal themes of being discontented and conflicted in his life. His tone is one of torment and conflict, as he is torn between life and death. For your essay, it may help to find quotes that support or provide evidence of this tone.
The themes of the poem are the narrator's discontent with life that co-exists with his fear of death. The narrator expresses the way in which his mind and soul are riven by indecision. Many of the lines feature opposing ideas, such as "I find no peace, and all my war is done." In other words, the narrator is not at war, but neither is he at peace. Another example is "I desire to perish, and yet I ask health." The narrator wants to die but also desires health. The word "yet" is in many of these lines, symbolizing the narrator's torn conscience.
The author uses figures of speech such as the simile "I burn and freeze like ice" to represent the way in which he is torn between opposing ideas, neither of which entirely pleases him. He also uses metaphors such as "That loseth nor locketh holdeth me in prison," meaning that he is neither free nor held in prison. Many of his lines contain an element of an oxymoron, or contradiction, and these figures of speech express the author's indecision and torn mind. When writing your essay, consider what these contradictions might signify; is there a pattern? What do they reveal about the speaker of the poem?
I'll let you think about the mood of the poem, given its narrator's tortured state of mind.