Is the network cable possibly faulty? With some networking hardware a green light indicates a 100Mbps network connection and amber indicates a 10Mbps connection; with no connection, the light should be off.
>>> As I cannot connect to the internet with the
>>> router I cannot get to it's settings which to
>>> my mind have become corrupt.
You don't need to be connected to the internet in order to access the router's configuration pages, although obviously the computer must be connected properly to the router itself.