I have forgotten (or lost) my rail card. What do I do?

Do not panic :)

Your ticket is not lost, this is the advantage of having an E-ticket. Your E-ticket is saved on your frequent traveller card mainly to save time during ticket inspection. Of course, it is also a convenient way to store your ticket as you don’t have to print anything. However, your E-ticket is always readily available to download again on the SNCF servers, so it can never be completely ‘lost’. You can also print it out yourself and just present the ticket on board.

The ticket controller should be able to find your ticket, using your name or file reference number. You just need to be able to present identification (Identity card, passport, drivers licence and etc.) if it is requested. 

If you have truly lost your card, just contact the relevant carrier (e.g. SNCF, Thalys or Eurostar) to request a new one.