I'm not able to type in special characters such as ú á í etc.   Is there a setting I need to change?  Many thanks.

That question is hard to answer without knowing anything about your setup.

Language?

Keyboard language?

Operating system?

Inkscape version?

English, but it is not my settings so much as others.  I write fonts, and I need to be able to tell others how to pull up alternate language characters.  I cannot personally type them in Inkscape (WIndows 10, Inkscape .92 and .92.4) but I can type them in other programs.   Thanks so much for taking the time!

So, you're currently doing it like this:

Hold Alt, then type numbers on the keypad

(that's what I found for Windows)

https://superuser.com/questions/110605/how-do-i-type-accented-characters-in-windows

In Inkscape, you type unicode characters like this:

https://inkscape.org/en/doc/tutorials/tips/tutorial-tips.html

(search for 'Entering Unicode values' heading near the bottom)

You can also use the glyph table, or copy-paste characters into your document.

I'm surprised that Windows doesn't seem to have a compose key to combine the diacritics with the letters, or some Alt Gr combo with the letter keys, as I have on Linux.

I've never found any way to type special characters like that in Windows!  I have always wondered how to do it.  I often copy people's names, because I can't type them properly!