Windows 7 home basic product key free

The key is listed on a sticker that resides either on the computers case, laptops body or in the case of the retail instillation DVD.
If it is not available on any of these locations and you have not yet reformatted your HD, call Microsoft, maybe they can support you.
If you have already reformatted, you are unfortunately SOL and must purchase a new license.

On a side note, it is against form rules solicit (or assist with) hacking, cracking or illicit product keys...