Edit: Welcome those of you who just upgraded to Linux kernel 2.6.31-20! This page WILL help you fix the sh:grub problem! 
I’m running Wubi with Ubuntu 9.10; I upgraded my kernel (from 14 to 19) and after a restart, landed at the GRUB prompt, “sh:grub>”. Yikes! I wasn’t actually familiar with the GRUB prompt before now. After some Google searching, here’s what I found: (keep reading, this is not the final solution, don’t bother following this link unless you’re just curious)
sh:grub Fix Wubi after grub-pc update on Karmic Koala
I followed those steps. He is very complete in his instructions. However, when I hit the “boot” command after loading up the 19 kernel, my computer just rebooted. I tried it again with my version 14 kernel and it booted into Ubuntu just fine. Okay, so I figured I’d just uninstall kernel 19 and go back to 14. Well, when I tried to do that in Synaptic, the generic meta packages depend on 19 so they would have been removed as well. I don’t know if this is a bad thing, but it scared me into more searching, where I found the real solution:
It’s quite simple; just do as the Solution section on the page says. I was careful to back up my existing wubildr file, but after rebooting, my boot menu was back! I chose kernel 19, and it booted correctly. Yay!
Oddly enough, if you do a Google search for “boot problems:wubi 9.10″ or even include site:sourceforge.net, you will not find that page above. Edit: it is now in Google, though what search terms bring it to the top of the results I can’t be sure.
Edit 3-5-2010:
I just upgraded from 2.6.31-19 to 2.6.31-20 without problem. I did not have to recopy the wubildr file or anything; it just booted correctly. So it looks like this is a permanent fix!
Thanks man! It worked for me, going from kernel 19 to 20.
REALLY… THANKS A LOT! I was worried that I’d have to do very complicated steps or even worst, have to reinstall and loose all my stuff.
You’re welcome! I wrote it specifically because I had a hard time figuring it out myself. I’m glad it was helpful! I probably should upgrade to kernel 20 too, I’m still in 19.
THANK YOU! I’ve been struggling w/ this problem for a while, cause I just can’t stop myself from installing the updates — so I ended up reinstalling each time (my files are stored on dropbox, so nothing lost, but still . . .) from 14 to 17 to 19. I just did the fix and am now happily in 20 w/o having to reinstall.
Yikes! Reinstalling is no fun. But hooray for Dropbox! I use and recommend it as well.
Haha, okay, so I feel the need to post my referral link now… If you’re reading this, and you don’t back up your files, think for a moment what would happen if your hard drive randomly died, like mine did a couple years ago. What all would you lose? Try Dropbox! If you sign up through this referral code, you and I both get an extra 250mb free. https://www.dropbox.com/referrals/NTM1MjIwNjk
Great job, worked perfectly!
[...] to Richard Carter for pinging back to my original blog post with what seems to be THE right way to fix this [...]
Thanks, this was a big help!
Thanks that was great. I can go back to using Linux again.
replacing the wubidlr file allowed me to see the famous sh:grub> screen. I’ve searched and I’ve no ‘vmlinuz-… ‘ like file in the /boot/ folder. Does it means that I dont have kernel?
Any suggestion?
Thnxs!
MANY thanks my friend.
i to was irked until i stumbled upon this page.
+10 points