I'm pretty sure that the only fix is to put the 64 bit disk in and do it all over. I don't think there is an upgrade path from 32 to 64 bit in Windows 8.
If you haven't installed a lot of other software it should only take about a half hour to get back to where you are.
Just do a full install so that it wipes the C:\ drive and gives you a clean copy of Windows.
If you have things you don't want to lose and only have one hard drive, you could create a second partition on your drive and move anything you want to keep to that, it will only format the C:\ partition.
But it would be better to have a external hard or second internal drive to back stuff up on.
I'm delighted to learn that I apparently can simply do a clean install with my 64 bit disc; I had thought that as my 32 bit installation had been activated that I couldn't reuse the code number to re-install using the 64 bit one.
I am 85 years old and have plenty of spare time to do the re-installation so there should not be any problem.
I'm 74 so you've got a few years on me. That's unusual around here.
I'm pretty sure Microsoft doesn't care which version you install as long as it's on the same computer and it's your registration number But if you do have any problems just call their support number and they will straighten it out.
Hey guys your making me feel like a young'n. I'm pushing 67. Made the same mistake when I first installed mine. Mike is right you can do a clean install using 64 bit. The product key will work for both. You should have no problem with it.