What is the difference between 我用 and 我弄 and 我做 ?Feel free to just provide example sentences.

Hello,
I think the meaning is quite the same among 我用/弄/做, but the situation might be a little bit different.
For example, you would say
做作業：我做好作業了 = 我做好了
做家事：我做好家事了 = 我做好了

But you won't say 弄家事、弄作業 or 用家事、用作業

But you could say
我做好作業了 = 我弄好了 (when people know what you are talking about, you don't have to specify the thing in this sentence)
我做好家事了 = 我弄好了

And also, when we say 用好了, it's more like you are dealing with something like "repair an air conditioner"
我修好冷氣了 = 我用好了
Or when you borrow an eraser from your classmate, and he/she asked, "Are you done right now? I need that." and you could say 摁摁，我用好了，還你。