What if nobody voted?

The law does not specify what happens. Though even if only one person votes, that vote counts.

If this happened in the US presidential election, then the US could go back to what was always done before the people were allowed to vote - the state legislatures choose the electors to the electoral college. There is no provision in law to run that election again.

If no one voted the state representatives would vote based on who they think the state would favor and the result would still be based off who wins the electoral congress

Things would either stay as they were, or, if that wasn't an option the thing being voted on wouldn't happen.

In the event of government, if the available candidates weren't voted for they'd have to find out why that was the case. Then they'd do what was necessary to attract voters by means of incentives.

there will always be staunch supporters the get the crap through the Conservatives in the UK got just 24% of the peoples vote one quarter they are in government the people were in as much disarray as you they were all dreadful candidates we are a disaster we voted BREXIT anything to get out of this hell hole the rich are fine like you but the majority of us it's absolute crap like you they do not even know they were shocked and now they want to change even the democratic vote to their way can you see where its heading Anarchy

If something wild happened and both major candidates were discredited and totally disgraced, such that there was a negligible turnout of say less than 4% of eligible voters, then a new election would have to be scheduled as soon as possible. It probably would result in Bernie Sanders running against Kadisch or Paul Ryan. Inauguration Day might have to be pushed back to around March 15.

Trump would still never be president.