If you keep around a bootable rescue stick like System Rescue it has a boot menu entry that will boot the Linux installed on your machine. Once you do that you can run a command or two to reinstall the bootloader. You can search the net or whatever at leisure since it will work fully.
Alternatively, if your system Linux is borked harder, you can boot the rescue Linux and use more advanced methods, depending on what’s wrong. The rescue Linux also has a graphical environment with browser if you need it.
At the very least sometimes you can figure out what went wrong. It may not be much comfort if you lost your system but at least you learn what not to do in the future. Too many people just say “oh, it just broke” and leave it at that.