Oh, man....I mistyped the first two lines (accidentally wrote "nbr" instead of "mbr") and didn't realize the commands didn't go through. The third, however (bootrec/fixboot) did.
Then I realized my mistake and retyped the three commands and restarted the computer. Upon restart, I got: "No bootable devices--strike F1 to retry boot, F2 for setup utility. Press F5 to run onboard diagnostics." F1 doesn't do anything; F2 takes me to the BIOS configuration page.
Did I make the problem worse? Is there anything I can do? I can still access the Recovery Options using my recovery disc...but now I am almost missing the original "Windows failed to start" message, which was less terrifying than this one.