miss printed code on back of card can't read

Physical damage or misprinting on a product key card cannot be fixed with software steps. When the printed code is unreadable, the only practical resolution is to contact official Microsoft Support so they can verify ownership and help with replacement or activation options.

Have ready:

• Clear photos of the front and back of the card (showing the misprinted area)
• Proof of purchase (receipt or invoice)
• The account intended for redemption

Then contact Microsoft Support through the official support channel for help with product keys and activation. They can review the case and advise whether a replacement key or other remedy is possible.

References:

• Can I speak to someone? -- Billing issues - Microsoft Q&A