Some weeks ago I had a problem with my computer and my ubuntu 18.04 crashed (here I provide some details). I don't have success runing the commands to run that ubuntu again. I had too much to do then I decided use another hard-disk and install ubuntu 21.04 on it in order to continue doing my work stuff.
So, I would like to know if there is a way to run or extract my data the old hard-disk, like my logs or configuration files and charged it into this new one hard-disk.
18.04untouched, you can certainly retrieve your data. Just attach the disk to a working Linux system.mountit with an arbitrary name, and then extract the data.