I opened a .docx document in Libre Writer, but all of the letter /Y/'s are missing from it. When I try editing to add the letter /y/, that doesn’t work either.
It isn’t the keyboard.
I’m using a MacBook Pro 2023 version, all updated; and the latest version of Libre Office.
Is there a solution?
Do you mean the common U+0059 LATIN CAPITAL LETTER Y (or its lowercase variant) or some other glyph looking the same? Your document is said to be a .docx. If it is an old document written with an old font (please mention the name), it may happen that this font was “converted” from antiquated 256-character set to present-day Unicode. This conversion moves non standard glyph from block 0x80-0xFF to Private Use Area Unicode block U+E000–U+F8FF. Of course such range is not accessible from the keyboard. And PUA is empty in “standard” fonts which could explain why the glyph is not rendered.
For better diagnostic, can you attach a sample file?
In a similar case, see this comment which might answer the question, Why can't I type the letter y in Writer? - #10 by ajlittoz