Grub starts but goes to resque mode without USB stick

I've installed debian 7.1 to my USB stick. For some reasons, installer didn't ask me about grub location, and just installed it.

Now, when I start laptop without usb I see grub resque mode ("Error: no such device: .... ") , when I start it with USB things go as supposed - I see menu and can boot to Windows and Debian.

I tried

grub-install /dev/sda update-grub

without success.

My partitions - /dev/sda - HDD, /dev/sdb - USB stick

What else should I do?