(source)
The thread of my hem of my Tshirt got broken and a short part of the hem is unsewn.
Is it correct to say:?
the hem came undone
the hem came unsewn
the hem is falling apart.
(source)
The thread of my hem of my Tshirt got broken and a short part of the hem is unsewn.
Is it correct to say:?
the hem came undone
the hem came unsewn
the hem is falling apart.
You can say "came unsewn." It is idiomatic and well attested.
The hem of her long dress came unsewn as soon as they got out of the station.
The idiomatic standard is...
The hem came undone (about a dozen hits in Google Books)
Note that although it will obviously be understood, Google Books reports no hits at all for the highlighted 3-word sequence in...
The hem came unsewn (link)
It may be worth noting that if a hem "comes undone", that can only really mean the stitching has "unraveled" (hems don't usually have buttons). Whereas...
His shirt came undone (link)
...is more likely to mean the shirt buttons came undone, rather than the stitching. But obviously you can say My shirt stitching is coming undone.
The other two sentences are correct. But this one sounds wrong
the hem came unsewn
If you really must use this construct then it should be
the hem became unsewn