I have a wall box with 5 light switches, the neutral 5 wires are tied together, I want to replace one of the switches, it needs the neutral wire to function. How do I find the correct neutral wire that belongs to this switch. Or any neutral will do? Thanks in advance.

If they are all on the same circuit then they should be together. If there is more than one circuit present then the neutral should NOT be all together (doesn't apply to a shared neutral circuit of course).

If they are all one circuit just connect to the bundle of whites.

There are two ways to connect a switches to circuits. One is called a switch loop. The power source is brought to the ceiling and a loop is run from the power source's constant "Hot" to the switch and then returned from the switch to the fixture.

Neutral (grounded conductor) is not used by a switch. That said, it can be used as a part of a switch loop to bring power to the switch, providing that the wire is also re-marked with Black or Red to show that this conductor is a "Hot" conductor.

The other way is to bring power to the switch via a supply source's "Hot" conductor. I strongly suspect that this is the setup you have.

Questions: Why do you have to change the Neutral (White) conductor? Where do you have to replace from (Source to switch/ Connection to fixture) which area?