Don't delete files like this, that's what the package manager is for. You're lucky that nothing depended on the files you removed. But you could have saved more disk space by removing the rest of the packages (aside from the kernel itself, there are modules and a few more things).
You can find out what package a file belongs to with one of the commands below (
dlocate is faster but must be installed first):
dpkg -S /boot/vmlinuz-*
dlocate -S /boot/vmlinuz-*
Once you've tested that a newly installed kernel works, you can safely remove the old ones. The package containing a kernel is called
linux-image-version-flavor. The command
uname -r shows which version and flavor you're running (don't remove that one!).
You might also have
linux-headers-version-flavor; that's useful only if you're going to compile additional modules not in the main kernel distribution.