My friend posted this in a conversation

ทุกสิ่งจะไม่หวนคืน..เหมือนเวลาที่ย้อนกลับมาไม่ได้

She said it means time will not go back as it was, however I can't quite figure out how she got that meaning.

ทุกสิ่งจะไม่หวนคืน..เหมือนเวลาที่ย้อนกลับมาไม่ได้

Everything will not return same time that return not able

That's how I literally read it and I know the syntax of Thai is different but this sentence still seems clunky to me. The concept of returning seems to be expressed redundantly even though different words are used หวนคืน and ย้อนกลับ. I would write it like this to more clearly express time will not return the same as it was before

ทุกสิ่งจะไม่หวนคืน..เหมือนมาก่อน

it's this last half that has me stumped

เวลาที่ย้อนกลับมาไม่ได้

I'm sure she's right but can someone explain why the latter part should be written the way she has?

My friend posted this in a conversation

ทุกสิ่งจะไม่หวนคืน..เหมือนเวลาที่ย้อนกลับมาไม่ได้

She said it means time will not go back as it was, however I can't quite figure out how she got that meaning.

ทุกสิ่งจะไม่หวนคืน..เหมือนเวลาที่ย้อนกลับมาไม่ได้

Everything will not return same time that return not able

That's how I literally read it and I know the syntax of Thai is different but this sentence still seems clunky to me. The concept of returning seems to be expressed redundantly even though different words are used หวนคืน and ย้อนกลับ. I would write it like this to more clearly express time will not return the same as it was before

ทุกสิ่งจะไม่หวนคืน..เหมือนมาก่อน

it's this last half that has me stumped

เวลาที่ย้อนกลับมาไม่ได้

I'm sure she's right but can someone explain why the latter part should be written the way she has?

The sentence is making a conparison. The first half loosely says that things don't come back, the second half compares it to time. Basically it says, "Things don't come back, just like time that can't be turned back." In English I might say something like, "Just as time cannot be turned back, neither do things (lost/past) come back." It's comparing "things" with "time-that-can't-be-turned-back"

My friend posted this in a conversation

ทุกสิ่งจะไม่หวนคืน..เหมือนเวลาที่ย้อนกลับมาไม่ได้

She said it means time will not go back as it was, however I can't quite figure out how she got that meaning.

ทุกสิ่งจะไม่หวนคืน..เหมือนเวลาที่ย้อนกลับมาไม่ได้

Everything will not return same time that return not able

That's how I literally read it and I know the syntax of Thai is different but this sentence still seems clunky to me. The concept of returning seems to be expressed redundantly even though different words are used หวนคืน and ย้อนกลับ. I would write it like this to more clearly express time will not return the same as it was before

ทุกสิ่งจะไม่หวนคืน..เหมือนมาก่อน

it's this last half that has me stumped

เวลาที่ย้อนกลับมาไม่ได้

I'm sure she's right but can someone explain why the latter part should be written the way she has?

The sentence is making a conparison. The first half loosely says that things don't come back, the second half compares it to time. Basically it says, "Things don't come back, just like time that can't be turned back." In English I might say something like, "Just as time cannot be turned back, neither do things (lost/past) come back." It's comparing "things" with "time-that-can't-be-turned-back"

Now that you explain it that way it makes more sense. I was trying to force it into her translation, but I think yours is more accurate.

It's written in a slightly poetic way too, could be a quote from a song.

Poetic language in Thai (as in most other languages, but perhaps even more so in Thai) is much more about beauty of sound and rhyme than the exact meaning being expressed as succinctly as possible.

This is why learning Thai from songs might make you a half-decent poet, but will not provide too many clues to the grammar and conventions of everyday spoken Thai.

CSS's interpretation is the same as what I see.