This is just the reason why you never should activate your pass until just before boarding the first train of your travel. If your plans change you risk loosing a travel day as you just did.

You can contact Customer Support through the form below and ask if they can give you a new travel day. Write your pass number and that you are currently travelling.

https://eurail.zendesk.com/hc/en-001/requests/new

Here is some useful information from the experienced travellers in the Community regarding both planning, reservations and activation of pass and travel days. 

 Planning

The rail planner is normally not up to date, as it only is updated once a month, so to be sure of the time table you better check the timetable and availability on the websites of the national railways. The bigger national railways, like DB (Germany) SBB (Switzerland) and ÖBB (Austria) cover several countries. 

 Reservations 

The advice from the experienced travellers in the community is to use other ways to make reservations than the Interrail/Eurail website.  You can look at the guide in the link:

https://community.eurail.com/train-connections-reservations-47/how-to-get-reservations-105

If you, after having looked at the guide, have questions about how to make specific reservation, please give your travel details (departure date, time and route) preferably in a new topic, and you will get advice.

Please note that Interrail/Eurail charges an extra fee of 2 EUR per person and train in addition to the fee for the seat reservation.

 Activation of pass

During the activation process, when you choose the start day of the validity of the pass, the first day of the validity period is automatically made a travel day, even if you don't enter a journey, the advice is therefore not to activate the pass before the first travel day as you only can deactivate the pass before 00.00 on the day the validity starts. If your travel plans change in the last moment you will loose travel days if you have activated the pass in advance.

It can be wise to make a test and activate the pass with a start date well in the future and then deactivate the pass immediately, just to see that everything works.

 Activation of travel day

The advice from the experienced travellers in the community is also never to activate a travel day, that is connect a journey to your pass and create the QR code, until just before boarding the train, otherwise you might loose a travel day if your travel plans change in a late stage  You can't delete a travel day in the past. A travel day can only be deleted until 23.59 CET the day before the travel day.

Je kan NOG een vervelende bijkomstigheid verwachten: wrs. is dus ook nu 1 dag IN NL aangeslagen-dus als je alsnog weg wilt en later terug per trein, dan zal dat niet lukken.

Je moet via special form zsm service contacteren-dan kunnen zij je een extra nwe dag bijschrijven EIGENlijk had overiegsn NS-via een van de zeer weinge nog daarzijne counters je een soort ´Gutschrift´ moeten geven-maar meestal zien ze dan allerlei problemen&bezwaren waarom dat niet kan. Je kan overigens ook in prinicpe via een chatrobot bij NS compensatie aanvragen-zie community.ns