have you tried another micro filter, they can fail after a period of time.
Does the phone ring if you plug into the rear of the master socket.( take the front cover off the master socket and you will find another socket to plug your phone into. Plug your phone into that and see if it rings.) If it doesn't then there could be a problem with either the phone or the line to your home. If it does work reconnect the master socket and plug the microfilter back in and then try again to prove that the phone works with just the mocrofilter and phone.
then plug your pc back in, if the phone fails to ring then it looks like either the micro filter or the router. Is this a new router or phone?