TL;DR
I deleted my /bin folder by running sudo make clean and managed to restore it. Now I want to verify that everything is working properly to prevent issues. I don't have enough reputation to just ask this in the mentioned link below.
Complete
I managed to delete my /bin folder by running sudo make clean to supposedly remove a software installed with the command make. Given my inexperience, I didn't see a difference and just believed that running it as root would help. Instead of that suddenly I didn't have make anymore and would receive the error about /bin/sh file or directory not found, same for essential commands like bash. In panic I restarted the system and it would get stuck at the login screen, with no way to call the terminal.
Looking for guidance I found these amazing answers. I tried the most voted answer by Ravexina, but unfortunately I couldn't manage to run chroot and also suddenly commands previously executed in the same session like mount couldn't be found anymore. By comparing with a LiveCD I could see that the whole /bin folder was missing, and not only some files like bash. I copied and pasted it by opening my broken system as root by following the suggestion by Dmitry Grigoryev which was my last alternative that made sense to me before of screwing things up more with more commands I don't fully understand.
Now I would like to verify that my files are all alive and I don't have missing dependencies or something like that. Running apt-get install --reinstall as suggested didn't prompt something apart of Reading package lists... Done | Building dependency tree | Reading state information... Done and the list of upgradable prackages.
