A disk error at that point means that either the Hard Disk is kaput and needs replacing or the boot sector of the Operating System is corrupt. In either case there is no keystroke sequence that can help.
In the case of the former you need to replace the hard disk however before you do that, I'd try a recovery disk. You should have made one but if you haven't, you'll need to borrow or buy one. (In the later case, from Lenovo.)