As we are limited in space, below are a few ideas to help get you started. Two of the poems, "The Ailing Muse" and "The Enemy" in Charles Baudelaire's The Flowers of Evil, share a similar theme concerning the apparent barrenness of the speaker's soul and how his youthful dreams, visions, and aspirations have been replaced only with the horrific fears and insanity that all he has suffered have brought on. In short, both poems concern the theme of lack of inspiration as the speaker's inspiration has been replaced with only fear and insanity.
We especially see the theme concerning lack of inspiration in "The Ailing Muse" when the speaker opens the poem by asking his "impoverished muse" what she has for him "this morning" in terms of inspirational thoughts. To be impoverished can mean to be completely devoid of "strength, vitality, creativeness, etc." (Random House Dictionary). Hence, in calling his muse impoverished, he is saying that his muse no longer possesses any creative abilities. What's more since the muses were understood to be Greek goddesses who inspired artists and writers, he is also saying that he himself is completely devoid of creativity. But more important is what he says his muse's, or his own, creativity has been replaced with. He continues to describe his muse as being full of horrible visions rather than anything more beautiful and inspirational. For example, all he sees in her eyes are "nocturnal visions," or the kind of creepy, dark visions we only see at night. He also says he sees visions of "insanity and horror forming" in her face. Hence, he is saying that his creativity has been replaced with horrible and insane thoughts. The horrible thoughts are further described when he begins to speak of demons, such as the "green succubus and the red urchin" who have "poured fear and love from their urns." A succubus is a demon that appears in the form of a woman with the express intention of seducing a man into intercourse to either devastate his health or outright kill him. Succubus's are understood to appear in the colors green, red, or blue. An urchin can also be considered a roguish or mischievous spirit, but since he describes them as a "green succubus and [a] red urchin," perhaps he is using both the term succubus and urchin to describe demons. Essentially, he is asserting that two demons have influenced his muse and therefore himself with both fear and the type of love that a succubus would be capable of, which is only passionate, lustful seduction. Hence, he is asserting that his creativity has been replaced with the horrific visions of fear and lust caused by these demons, and it's these visions that are both driving him insane and influencing his poetry.
The theme of being deprived of creativity and inspiration can further be inferred in "The Enemy" in which the speaker essentially asserts that his creativity and inspiration were destroyed along with his youth. Baudelaire's central theme in this poem concerns the passage of time. By the end of the poem, the speaker calls time an "obscure enemy that gnaws at my heart / Uses the blood that I lose to play my part." In other words, he sees time as an enemy because it has destroyed everything that was young about him, such as his heart, which metaphorically refers to his hopes or dreams, and it's those hopes and dreams from which he derives inspiration. In the beginning of the poem, he even says that his youth was nothing but agony, and so, apparently, nothing is left of what typically belongs to youthfulness, such as beauty, innocence, and virtue, as we see in the opening lines, "My youth was nothing but a black storm ... Nothing's let of the fruit my garden held once." He even states that he should re-plow his fields but wonders "if the new flowers [he] dreamed" will even be able to take root in the soil, meaning, he wonders if he'll even be able to rejuvenate his heart, soul, and mind enough to think of new dreams and aspirations for himself, which in turn will incite new inspiration and creativity. Hence, just like "The Ailing Muse," while "The Enemy" also concerns youth and dreams, it also concerns being deprived of inspiration. The only difference is that in "The Ailing Muse" the speaker blames his lack of creativity on his horrifying, lustful, and insane thoughts, while in "The Enemy" we learn of a possible reason for his horrifying, lustful, and insane thoughts, that reason being the "black storm" of his youth, or whatever horrible things happened in the speaker's youth to age his heart, mind, and soul.