Actually — known trick: (shift +1) for the real message: i → j d a n l w d → e b o m x e w y → x z p y → q z a n → b o b y w → c z x b y w → c z x b r a y → c s b z w y n d w z → x z o e x a

Result: v--- qnayjq jl cl na olj olj oenl jlaqjm — also not quite English.

w → q (no) — so that’s not right. Given the pattern "i---" at the start, maybe it's on "i---" → v--- which doesn't help. But "byw" twice — could be "the" or "and"? Possibly the phrase is: "I--- [something] [something] and the the [something] [something]" — maybe "bray" = "from" or "like"?

Given "byw" appears twice and "bray" likely "by" + "ray"? Could be (a↔z, b↔y, etc.):

It looks like you're working with a simple cipher — likely a shift cipher (like rot13) or keyboard shift. The string "i--- danlwd wy py an byw byw bray wyndwz" appears to be a jumbled or encoded phrase.