Help LCD with 2 wire Connect (Idea)

[NavMicroSystems]

Ken i Use 4 Resistors of R1=10k,R2=20K,R3=30K,R4=40 AND USE THE
ADCIN VoltChannel, Voltage

IF Voltage > XXX THEN THIS IS = BUTTON ONE AND SO ON

In principle yes.

There are many different ways to set this up,
it depends on what type of buttons you have.
if they have NO + NC contacts then you could setup a real R2R Network
this would allow to detect any combination of keys pressed.
(more than one at a time)

The simplest (with primitive NO-pushbuttons) would be:
5 resistors all of the same value (say 2k2, or 4k7) in series.
(but if more than one key is pressed at a time you will only detect the one pressed closest to the input.)