You can get to the command prompt by pressing shift+f10.
Can I, install another copy of win 7 into that 18 gig partition
Then ( assuming I can boot into it) use that to do a repair install
No - the repair install will only try and repair your currently booted os.
However, a fresh install onto the 18 gb might fix your issue anyway.
BTW - Bootice is probably the most useful tool for anyone multibooting.
No instructions needed - GUI will adjust to English if you are running English os Attachment 218123