I'm helping a friend out with his pc, that has Windows 8.1 installed. There is two user accounts on the pc, his and his wife. His account works fine, but his wife account is not accessible. When you boot up the pc only his account available. After you login into the computer and try to switch user. The only option that comes up is his account again! Check control panel and both accounts are there, so I try using update and recovery feature. Which tells me files are missing and insert media(installation disc). But when I do that it tells me media is invalid. Any help or suggestions will be greatly appreciated thank you.