Windows says is not genuine.

1. Your Windows 7 is not legal.
2. You can't find the COA sticker which should be their.
3. You will have to buy a Windows 7 COA and then we can help you install Windows 7.

It is not legal to sell a machine with Windows installed unless either
1) It has a COA sticker for the installed version and edition of Windows on it - and a way to reinstall that edition.
or
2) there is a retail license for the appropriate version and edition of Windows, together with the appropriate disks and Proof of License - and the original receipt for that license package.

Since you appear to have neither, then the person who sold you this machine is assumed to have committed fraud, and software piracy.
You should attempt to claim a refund (pretty hopeless after this length of time), as well as report them to MS and to your local law enforcement and better-business organisations.

A new definition of friend of is needed.

From post #5

It does not. I got this version of Windows from a friend who is reputable. He got it from a computer he dismantled for parts a while ago. He was doing me a favor.