What travels have you made in Sweden so far and what travels are you planning to make? Can you post screen shots of your "Trip" ? Remove all personal details. 

As u see I need to make sure the outbound is for tommorw, because of the train schedule 

Did you travel by train from Sweden when you started your trip?

Yes 

You should have bought a normal ticket from Kungsbacka to Göteborg today. When you activated that trip you got the question if you wanted to use an outbound/inbound day and you accepted that.

The ticket was free tho, no seat reservations. Is their any way to change this? Because their is nooooo trains from tommorw. This is the only way without reservations

You can always try to contact Customer Support but I doubt that you will get an answer before tomorrow morning. 

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

Write your pass number and that you are currently travelling. 

Did yoy travel in Sweden when you started your trip?

No I didint 

What travels have you made in Sweden earlier than the journey from Kungsbacka to Göteborg today?

Just my Inbound journey from Stockholm when I started 

Ok. I doubt that you will get any answer from Customer Support before 7.15 tomorrow, and even if you get an answer there is no guarantee that they will give you another inbound travel day. I guess you just have to buy a normal ticket back to Stockholm .