I stored my car for about a year in a storage unit. When I started the car after a year I found that the brake master cylinder didn't have any fluid in it. I started the car and drove it around the parking lot only to find that I didn't have any brakes.
I stopped by shifting into neutral and using the E-brake. I guess the fluid leaked out of the master cylinder or just evaporated if I didn't have a good seal on the master cylinder. After putting fluid in it and bleeding the brakes everything worked like a charm.