[other] Stuck in grub2. Please help!

Hello, everybody,

I have been moving and resizing partitions with gparted, but I forgot to run update-grub after that. Now, the system boots to a grub2 command line (version 2.02-beta2-9ubuntu1.3, if you need to know).

I would like to boot again from the USB to run update-grub and hopefully fix the boot menu, but I am not familiar with grub.

ls shows a list of partitions, and (hd0,msdos1) looks like the bootable USB. There are also a few partitions in (hd1, ...) but I don't think any of them is usable.

I have tried the following, which I read here:

linux (hd0,msdos1)/ntpasswd/vmlinuz root=/dev/sdb1
initrd (hd0,msdos1)/ntpasswd/initrd.cgz
boot