Hello, I’m Quinn and I’m here to help!
If you purchased Office Home from a physical store, the retailer may be able to verify your purchase and assist with a replacement.
I also recommend reaching out directly to Microsoft Support. Explain that your product key was accidentally scratched and is now illegible. With proof of purchase, they can usually issue a replacement key or provide another way to activate your Office software. You can contact them here: https://support.microsoft.com/contactus/
Just to clarify, did you buy this as a physical card from a store, or was it shipped to you by an online retailer?