This is my standard advice for RTS (returned to sender) packages. Take the parts that are relevant to your situation.
You have a few options. You should decide which route you'll be taking and communicate with the buyer, but wait until the item is returned (and delivered) to you before you take any of the following actions.
You can refund the buyer the item cost minus original shipping and minus a portion of your eBay final value fees (fee credits are prorated on a partial refund so you won't get back fees on the shipping amount you withhold). Go to your orders page, find the transaction and select "send refund." On the next page enter the amount. After that, relist the item and if you still want to work with this buyer you can tell them to repurchase it with the correct name/address.
Have the buyer sort out their address issue then pay for re-shipping. Use PayPal, Venmo, Zelle, etc. This is post-sale so it's OK to exchange email and phone. It's also OK to ship to a different address because it's technically not tied to the original transaction. You will not purchase the shipping label through eBay or upload tracking to the original transaction. You will purchase the label from an alternate site like pirateship.com and you can send the buyer the new tracking # through e-mail or eBay messages.
A different way to accomplish buyer payment for re-shipping is to create an eBay listing for the shipping cost in the services category, bumping it up to factor in eBay fees, and have the buyer purchase it, entering their correct address at checkout. You can purchase a shipping label through eBay for that transaction.
You can cancel the transaction selecting the reason problem with buyer's address which will trigger a full refund to the buyer and your final value fees will be credited.
You can do nothing. The buyer's Money Back Guarantee protection is voided when there's a package delivery attempt to the address on the order. I don't recommend this because even though you'll win an INR (item not received) claim on eBay, there's nothing stopping that buyer from going to their credit card to file a dispute and why deal with all that? I also think handling it before it gets to this stage with a partial refund is the 'right' thing to do if you're not going to make reshipping arrangements.
You might also want to direct the buyer to this page so their address is updated for future purchases: Account Settings: Addresses
