NFT: Attic ladder extenders

then someone installed the wrong size ladder. I can't believe someone cut it that short. The only thing I can think of is to remove the lower fold away portion and rebuild a new section that is the correct length and touches the floor and then reattach it. Some of the ladders can be taken apart, which means you could use some of the treads. The others would have to be added. And all of this assumes that the ladder would fold back up when you are done, which it might not.
I'm not sure I would trust extenders for that amount of distance, especially if you're carrying something heavy. The last thing you need is a ladder-related fall or accident.
The safest thing is to replace the whole ladder. I had to install a new fold away attic ladder in my house back in January. I ordered it from the Home Depot. I've never installed one before, but it was pretty easy.

and is it the folding ladder like in the image below usually for an attic?

If so, I would replace the thing. Depending on material it's only a few hundred dollars.

they make wood, aluminum, whatever.

I did mine to my attic and the only hard part was shimming it, but I was replacing existing steps that were just old and breaking down.

Most stowaway attic ladders are designed for 8 foot ceilings. We have a 9+ foot ceiling in the garage, so the ladder is a bit over a foot too short. Sounds like you have a more extreme version with a 10+ foot ceiling.

You have two options as I see it. You can replace the entire stowaway assembly with a longer one. Or you can live with it and fashion a step platform to place the base of the ladder on. Something you can shove into a corner when not in use.

Replace the ladder with one that's the actual length you need. Way too many ladder related injuries occur under normal circumstances. You don't want to increase the odds of a fall.

In an attic. Conditions aren't ideal and if it's truss construction you can overload the structure.

making sure to provide for anti-skid on the bottom, and put some angle aluminum to make sure things are lined up..maybe drill holes so a quick release pin can pass through the ladder and the riser box to unitize them.

...you wont need to keep any short step stools in the garage, certainly(!)