How to release these drawer slides

I'm guessing these shattered because of shock or perhaps from being fully extended more than normal since the front wheel takes a lot of the weight when drawer is fully extended. The rail is acting as a lever where 10kg in the front of the drawer could easily be the equivalent of 100kg on that wheel when the drawer is fully open. The other thoughts are if someone where to lean on the drawer or if the cabinet was being moved and dropped.

I've seen replacement wheels, but they tend to be for specific rails/sliders, and I doubt you'd get a good result without a perfect match. For replacing the entire slider, I'd look for a replacement with a high weight limit. I've seen sliders in the US that are designed for 50kg, which I'm guessing would more than handle your load.

There are a few tricks to drawer slides. The main things to get right are to make them parallel and co-planar (same distance from the case bottom on the right and the left side, as well as level front-to-back in the case). It helps if your case is perfectly square, so really focus on that. You'll want to determine your drawer width based on how thick the slides are.

A good rule of thumb is to always try new drawer hardware in a scrap case to get a feel for how it works. That way you'll work out any issues and not-so-obvious dimensions without having to fill in bad screw holes on your real project.

Here is a brief blog post on some Kreg jigs that assist in this process, and here is a YouTube video on how to do it using just spacer blocks to get everything flush and level. Here and here are some succinct points to follow and another good video. And last but not least, a good article on Rockler's site with some recommendations for jigs that ease the process.