I did not know any of the programs mentioned in the post, but some of them seem really nice. Can someone who thinks aliases are a better solution please explain why they think so and what is their advantage over these projects? Do they have any pitfalls that you are aware of?

I believe that if I use a command sparsely enough, I will forget the created alias name just a few days later than the actual command.

Sorry, can’t resist: it would not be 6.5 % of Linux users, it would be 6.5 % overall. That would mean about 54.8 % of Linux users.

Give testdisk a go, see for example this tutorial. It is a terminal utility, so it might take some time to get used to it. But no one can guarantee that it will successfully recover anything, the deleted files stay on the disk only as long as they are not overwritten.

Do you have any idea why the files disappeared after reboot? One thing that comes to mind is that they might have been saved in /tmp, in that case I believe recovery would not be possible.

Regarding to which files you should recover, try all of them and see if you have any luck.

Good luck with recovering the files!