idiot changing registry

Oh god I need help. I did something retarded in my registry to change my active hard drive's letter. Now the hard drive won't boot all the way and i'm having to post this from another hard drive. Is there a way to edit the registry on that hard drive from this one?

>>1
WARNING OPENENING REGEDIT CAN COMPLETELY MESS UP YOURE COMPUTER BEYOND HELP DO NOT OPEN REGEDIT WARNING DO NOT OPENR REGED IT OK GOT THAT NOW DONT DO IT IN THE FUTURE

BY THE WAY I DO IT ALL THE TIME WITHOUT EVER MESSING ANYTHNG UP I JUST WANTED TO WATRN YOU NECAUSEC THAT IS VERYYYY DANGEROUS THAT REGEDIT THINGS OK!!!!

OH OKAY THANKS THAT TOTALLY HELPED

hope you got 10 bux