Milton Keynes is on the West Coast mainline, connecting London to the Midlands and North of England and Scotland.
It is served by London Northwestern Railway and Avanti West Coast.
A spokesperson from London Northwestern Railway said: “We are working closely with Network Rail to resolve the disruption as soon as possible. In the meantime, ticket acceptance is available with East Midlands Railway and Transport for London Overground.”
Avanti said tickets would be accepted by other operators on “various routes”.