One of mine broke several years ago. Sitting in the kitchen early one morning drinking a cup of coffee when it broke, and I thought something had fallen on the house.
Called a local garage door company in business for about 60 years to come out and fix it. Told them its a 20ft wide door as I knew that's sorta unusual. The guy there said they don't stock any springs for 20ft doors as they only run into one every couple years, and that they'd need to come by and check the spring dimensions before ordering. Said it would take a couple days to get the springs. One of their guys was headed toward a job in our end of the county that morning, and he'd call him and have him come by and check it on the way to the other job.
The man arrives and gets the dimensions, and then, in about 10 minutes, he prys the coils apart at the break and temporarily fixes it with a couple cable clamps so we can get the cars out.
The house was 40 yrs old at that time, and I knew a few of the rollers were bad, so I told him to replace all rollers when he came back. He recommended replacing the lift cables as well as he saw a couple frayed places when he inspected them.
2 trips, labor, 2 springs, full set of rollers, and a pair of lift cables. Total bill was $260. At that price I have zero interest in learning how to do it myself.