" I cannot find that on the DB website."
I assume you are talking about missing a train specified on a Savings Fare ticket. It is spelled out in the AGB (Conditions of Carriage), which is in German. If you miss a specified train due to a fault of the Bahn, you can take the next available train. It's probably best to go to the ticket counter and have them mark your ticket for the next train rather than just get on the next train.
This happened to me in 2008, when I was on a regional train with a SparPreis ticket to Nordhein. The train unexpectedly stopped for half an hour in a small station, therefore getting to Nordheim to late to catch my IC to Karlsruhe. I went to the ticket counter where the clerk checked the data base to confirm that the regional train had indeed arrived late, then marked my Savings Fare ticket with the next train, an ICE, which actually got me to Karlsruhe earlier than the IC would have (but no free coffee).
Of course, on a Standard (Full) Fare ticket is wouldn't have mattered, as you have the rest of the day, and probably the next day as well, to finish the trip.