I am not an experienced Ubuntu user. I updated my existing 12.04 until no more updates were available and then I chose to upgrade my system to version 12.10. All went well (or at least I thought it did) until I was prompted to "Restart" the system. Once I restarted the system I could hear my HDD doing its thing and then saw the screen come on and it said something about either waiting for something to happen (which I chose to do) or press "S" to skip mounting or something like that (I couldn't read it fast enough). Anyhow, the computer locked up and it wouldn't boot into Ubuntu. I powered the system down and restarted it hoping to see the message again, but it didn't return. It just locked up during the boot process and I haven't seen my login screen again.
I have a dual boot configuration with Windows Vista Home Premium (32-bit) and I have never had a problem upgrading in the past. My processor is an AMD 64-bit and I have always used the 64-bit version of Ubuntu with no problems.
I would appreciate your help in this matter.