i just bought an led driver. but it has two white wires for the mains. I was wondering which wire is live and neutral.
It doesn't matter.
As AC current alternates, the only difference between the two input cables is which is connected to ground (in your switchboard and/or at the supply transformer).
The only case where they need to be differentiated is when switching - you should not switch neutral, except in very few cases where you also switch phase.