Have your brake system checked immediately! (by a proffesional)
You probably need to change your back brakes.
It means there is brake problem somewhere, maybe the back brakes.
you have brake fluid leak in your brake system somewhere that need to be check.
Probably a rotted out brake line sprung a leak, check the brake fluid reservoir.
Any sudden brake loss can be the cause of 1. brake line damage 2. master cylinder disfunction
Leak in hydraulic system? Brake linings worn? Brake linings glazed?
It locks the brakes when the vehicle or trailer is not in use. It also engages if air pressure is suddenly lost.
If you mean the brake itself, the parking brake lever pulls on the cables which attach to the rear brakes and manually tighten up the rear brake shoes. If the brake isn't working either a cable has broken or the problem is in the rear brakes.
Brake Booster needs replaceing
need more brake fluid
Don't drive and take it straight to a garage 'cause it will empty your brake cylinder.
The brake pads are a part of the braking system. Many people do refer to the brake pads as "the brakes", but you'll need to make sure the rotors and calipers are working properly as well. Additionally, The term 'brake pads' are associated with 'disc brake' systems. Earlier vehicles had 'brake shoes' which were associated with 'drum brakes'. Depending on the year of the car, front brakes could mean either and is a generic term.