I accidentally deleted my ubuntu boot folder.
i get a grub-rescue prompt when i intend to boot the computer.
i need help please.
Boot into the rescue mode and see if you can reinstall the kernel. That should allow you to boot the system.
One bit of gratuitous advice - leave /boot alone! Once you are a "Linux Expert" that may not be necessary advice, but until then, leave well-enough alone... :-)
Open terminal then reinstall Grub:
sudo grub-install --root-directory=/path-where-it-was-mounted/ /dev/sdx
/dev/sdx your system root partition
Did you try to run the boot repair disk ?
Edit: sorry, this is 6 months old :) I guess the OP managed to boot.