The ticket you bought has a ToS attached to it, but basically it boils down to that DB is only required to get you from A to B, but you're not entitled to any s

The ticket you bought has a ToS attached to it, but basically it boils down to that DB is only required to get you from A to B, but you're not entitled to any specific mode of transportation other than "preferably by rail". While the train may have ended surprisingly, since other trains are still running, DB's opinion is that you can figure out the rest.