list_select_item i think this is it...
if m wrong plz correct me

Hi Sowmya,
List_get_item_num("","",number);
This function returns the numeric position in a list of an 
item
 arg1 is the list name
 arg2 is the item string 
 arg3 is the returned item number.


Ratna Rao,
9833847339.

list_get_item_info();
contains 4 parameters.i.e.list,item,state,output value
it returns the state of a list box

list_select_item ( list, item [,button  [, offset ] ]);
list - logical name
item - selected item
button, offset optional.
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list_get_item("list",0,lvalue); used to count the list box 
values.
list - list's logical name.
0 - which value u want to get
lvalue - variable, to store value of 0th position
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list_get_items_count("list",outval);
list - logical name of the list box
outval - variable used to store the output value
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