Your garage door can stop working properly for any number of reasons. Although the springs do a great job when it comes to lifting up doors that weigh hundreds of pounds, they will eventually break down. It is imperative that you get your springs replaced as soon as they break down because it will cause a whole headache of issues that you don't want to deal with.
Spring Cycles
Manufacturers rate springs with cycles, which determines how long they're expected to last. You can find high-quality springs that will keep doing their job for at least 30,000 cycles. Assuming that you have a properly operating garage door that is opened and closed about 6 times a day, you can expect to get about 11 years of use before the spring breaks.
Spring Types
There are two common types of springs used on residential garages: torsion and extension springs. A door that uses torsion springs typically has one torsion spring mounted above the door with a spindle running through it. When the door opens or closes, the torsion spring clamps down on the spindle or uncoils - releasing tension or generating tension to help move the door. Extension springs are typically mounted on either side of the door.
Spring Repairs
The springs can break down over time as you've already learned, so what are you supposed to do once they do?
Some potential telltales of a broken spring include: The opener strains to lift the door; you heard a loud snap or similar noise while the door was operating previously; the door is hanging at an angle, etc.
A licensed professional should be called if you ever have trouble with your springs. In particular, the torsion-type door springs are under high tension that needs to be released properly to avoid turning the spring into a potentially lethal projectile if it breaks loose. If you install the springs but don't balance the door properly, then the springs will become worn down much more quickly.