Computer won't boot-cycles through loading screens and restarts?

It sounds that you have corrupted your system. The updates are not completed when you shut it down, that's why it has been corrupted. If system restore failed, no other option but to re install your OS, which is Vista. If you have the recovery partition on your hard drive, you can use it to re install your OS. If none, you will need an OS disc to reinstall your OS, which you have to purchase if you don't have it.