Im new to this so apologies if something like this has already been asked and solved but here goes...
I have an 03 MK6 Ford Fiesta that I use daily for short journeys. The other day when I was driving it everything was fine then I went to brake and suddenly I heard a sort of bang and the brakes failed and I went straight across a roundabout (managing not to crash) I can hear a sort of grinding scratching sound on the drivers side everytime I push down on the pedal. I have had the wheel off and brake off and cant find any problems?. The brake pad still has a fair amount of tread left (on both sides) so it cant be that. Also the grinding hasn't built up and got worse it was just all of a sudden! any ideas? would much appreciate the help!