first thing is dont panic, there are ways to resolve everything, even if it means reinstalling. i assume you had everything backed up before installation.
do you get a system restore option when the repair option appears. if you do, try the restore option, as the corruption may have taken place when you hard re-booted your p.c. you may be better doing another fresh install anyway, in case files have been corrupted. can you burn the iso to disc and install from the disc?
one of the really cool things about 7 is the fast, virtually unattended, installation.
hope this helps