Perhaps a late response: I have made an address.tns program that will fit the purpose. It holds a spreadsheet containing 1st name, surname etc. some programs and a calc page for running programs. Its output is a text box and all of it is standard programming, that is, without scripting. It is quite easy. If you want the full address book program, just let me know. I rewrote some code for your request.
How (new program):
(1) Create a blank calculator.
(2) Create a spreadsheet page with a column named "s_name" . From another spreadsheet, import the student names. (In Excel: copy a range in a column, then in TI Nspire, right click in the first cell (A1) and press 3 Paste). Make sure the originating text, in Excel, is formatted as text so, after pasting, it is in quotes when accessing the cell. Otherwise, type the 24 names, using a quote to start a name, then a letter or space to enter the name.
(3) In the third page, input a program (name it whatever you like; I used programs named a00_… to a21… to get them on top of the var list). I rewrote some stuff to adapt it to your needs. Don't forget to check syntax and store, then save the .tns as "choice.tns", something like that.
(4) On the calculator page, press Var and select a_09_show(). A random name will appear in a text box.
d:=dim(s_name) © dimension of s_name, the variable representing
© the spreadsheet column holding the student's names
If i>0 and i≤d Then
Text s,0 © show all in a text box only
Text "That record doesn't exist",0 © if result of randint > d just to make sure
Now, by the way, if you add names to the spreadsheet, you don't need to change the program, because d:=dim(s_name) takes care of that…