What is the model of the computer?
On that model their is a sticker on the bottom of the laptop.
Will look like this: http://digitizor.com/wp-content/uploads/2010/10/win7productkey.png
If the sticker was torn off and you already wiped the system with the Windows 7 installation there is no way to retrieve the code from Toshiba or Microsoft. You would have to buy a new license Windows 7.
Windows 10 is newer. But they still sell Windows 7 on Amazon.
Did 10 work?