How to get a refund for a reservation when the train is cancelled

Hello;

In order to do my trip I purchased three 4-day passes, booked seats on several trains and booked hotels. 

After I had everything set and planned, I received two emails from Thalys informing me of the suspension of two trains (one on the 4th, between Paris and Brussels and the other on the 11th, between Cologne and Paris). 

These cancellations affected tremendously my vacations, resulting in the suspension of my trip and considerable financial loss (cancellation of the interrail pass, reservations for seats on trains and hotels). 

Can anyone be held responsible for my losses? If yes, what procedures should I take? 

Thanks