Hopefully, you'll need no more explanations regarding my identity. Ok as it is. Might also see "Hopefully, you'll need no more explanation regarding my identity." - To explain how did I emerge suddenly from wherever I vanished in. Nope: "vanished in" - To explain how did I emerge suddenly from wherever I vanished to. - Aimlessly, I picked it up. Fine. - your name was written there along with many others. Fine - I gathered what I wanted to say. Not incorrect, but I cannot imagine where it would fit. - I gathered what I wanted to take. <-- makes sense - I collected my thoughts about what I wanted to say. <-- another possible - I gathered my thoughts about what I wanted to say. <-- another possible Sorry, I can't see how to sensibly use "gather" things with "say".

- your name was written there along with many others. Your name was written there, along with many others. - Hopefully, you'll need no more explanations regarding my identity. OK. You could change explanations to explanation. - To explain how did I emerge suddenly from wherever I vanished in. As a reader I do not understand what you are trying to say in this sentence. Are you trying to start to explain how you emerged suddenly? - I will explain how I emerged suddenly, after vanishing from sight. - Aimlessly, I picked it up. As a sentence this is fine but from understanding it needs context which I assume comes from previous sentences. In this case you refer to 'it'. If the sentence before read: I saw a ten pound note on the ground. Then the 'it' would be the ten pound note. If your sentence needs to make sense on its own then you need to replace the 'it' with what it is. - I gathered what I wanted to say. Looks fine from sentence structure but lacks meaning. Most people would not say they gathered what they wanted to say. I formulated what I wanted to say. Would work better.

they are correct [emoji]