Unable to boot post upgrade to 12.10 from 12.04 on a dual boot PC

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http://askubuntu.com – I have a dual boot PC with Windows 7 and Ubuntu. Last night I upgraded from 12.04 to 12.10 and since then I have not been able to boot because the PC goes into grub rescue with the error "File not found". I have tried the following steps: set prefix=(hd0,msdos5)/boot/grub/i386-pc/ set root=(hd0,msdos5) insmod normal I get error symbol not found : 'grub_disk_dev_list'. When I try: linux /boot/vmlinuz-3.2.0-32-generic root=/dev/sda5 ro I get error - command not found 'linux'; same for initrd I am not able to find out what sdXX to set also. (HowTos)