This is what insurance is for. You file the claim, get your payment and the insurance carrier fights it out with the airline.

As a general proposition, when you fail to fly a segment of a ticket, the entire ticket is cancelled. Whether the ticket has any remaining value will be determined by the terms & conditions of the ticket you purchased.

You can ask KL to reinstate the return based on your circumstances and the backup of a letter from your physician explaining the nature of the emergency and further that you were not physically able to call because you were in the ER.

As to the issue of the local KL handler not being available over the weekend, you are not excused from contacting the carrier elsewhere. It can be expensive, but that is what Skype covers.