Data transfer to new computer with WIN 7 changed it to WIN 8 from old computer

[TKNUCKLES]

I had purchase a new HP computer with preloaded WIN 7(which is what I want). My old HP had WIN 8.
When I transferred the data files to my new computer it transferred WIN 8 with it.
I've tried to go back but the computer doesn't recognize the Prod Key for WIN 7 that came on my new computer.
Since it was preloaded with WIN 7, it didn't come with discs.
I'm scared to continue to mess with it and need some help.

 

[TrainableMan]

There may be a boot option to restore the computer to original factory settings.

It is highly unlikely copying data could trigger a Win8 install. More likely, if you can restore it, that then you need to disable automatic windows updates at least until you can hide all of them that involve a Win8 upgrade.