Brake problem

We decided to go for a ride to Tuusula "Lotta-museum" today. Lottas were women who served in the Finnish wars for example as nurses. Anyway in the middle of the way, I noticed that my front brakes are not working properly and eventually they disappeared all together. I managed to drive to our destination with shaky hands but did not have courage to drive back home without the brakes - so we picked the bike later. The brakes have been problem all the summer, they seem to work when they please - but they have never disappeared totally like this. So not so good experience today but at least I'm back home in one piece and learned some valuable lessons too.