I recently had an issue with my acer 4736z notebook because I was having a blank screen after booting the OS, then someone told me to use the parameter GRUB_CMDLINE_LINUX_DEFAULT = "quiet splash acpi_osi = Linux" after quiet splash inside the grub. It worked for me, but since then I can't install a thing or update anything on Linux because it says

Removing linux-image-extra-3.5.0-17-generic ...
Examining /etc/kernel/postrm.d .
run-parts: executing /etc/kernel/postrm.d/initramfs-tools 3.5.0-17-generic /boot/vmlinuz-3.5.0-17-generic
update-initramfs: Deleting /boot/initrd.img-3.5.0-17-generic
run-parts: executing /etc/kernel/postrm.d/zz-update-grub 3.5.0-17-generic /boot/vmlinuz-3.5.0-17-generic
/usr/sbin/grub-mkconfig: 11: /etc/default/grub: GRUB_CMDLINE_LINUX_DEFAULT: not found
run-parts: /etc/kernel/postrm.d/zz-update-grub exited with return code 127
Failed to process /etc/kernel/postrm.d at /var/lib/dpkg/info/linux-image-extra-3.5.0-17-generic.postrm line 328.
dpkg: erro ao processar linux-image-extra-3.5.0-17-generic (--remove):
 sub-processo script post-removal instalado retornou estado de saída de erro 1
Removendo linux-image-3.5.0-17-generic ...
Examining /etc/kernel/postrm.d .
run-parts: executing /etc/kernel/postrm.d/initramfs-tools 3.5.0-17-generic /boot/vmlinuz-3.5.0-17-generic
update-initramfs: Deleting /boot/initrd.img-3.5.0-17-generic
run-parts: executing /etc/kernel/postrm.d/zz-update-grub 3.5.0-17-generic /boot/vmlinuz-3.5.0-17-generic
/usr/sbin/grub-mkconfig: 11: /etc/default/grub: GRUB_CMDLINE_LINUX_DEFAULT: not found
run-parts: /etc/kernel/postrm.d/zz-update-grub exited with return code 127
Failed to process /etc/kernel/postrm.d at /var/lib/dpkg/info/linux-image-3.5.0-17-generic.postrm line 328.
dpkg: erro ao processar linux-image-3.5.0-17-generic (--remove):
 sub-processo script post-removal instalado retornou estado de saída de erro 1
Erros foram encontrados durante o processamento de:
 linux-image-extra-3.5.0-17-generic
 linux-image-3.5.0-17-generic
E: Sub-process /usr/bin/dpkg returned an error code (1)

I already tried to remove older kernels but it gives me the same message. Do you have a clue about what should I do?