Recovery windows 10 home key

Solution 1:

Is there any way how can i restore my old serial key?

Windows 10 OEM license keys are stored in the ACPI table. The Windows installation environment automatically detects the key stored in the ACPI table. While it's possible to retrieve this key yourself, it isn't necssary, since the installation environment can detect it.

Because its not anywhere in my box from notebook.

Unlike Windows 7 license keys which were printed on the COA sticker on the device, Windows 8+ OEM license keys are stored in the ACPI table, they were NOT printed on the COA sticker itself. The Windows 8+ installation environment detects this key automatically.

In order to reinstall Windows 10 Home, you will have to download a Windows 10 Home ISO, and then install it. When prompted to enter the license key, you can skip that step, once installed Windows 10 Home will automatically activate.