My seed restored but there was a passphrase and I don't remember it

If your twelve words were accepted without an error and the wallet shows nothing, there are two possible explanations. Rule out the cheap one before assuming the expensive one.

Why nothing warns you

The passphrase is not a password checked against something stored. It goes in as an ingredient to the calculation that turns your words into the wallet's root. Change one letter and you get a different root: legitimate, functional, and empty because it never received a payment.

That is why there is no "wrong password" screen. The software has nothing to compare against. It ran the calculation you asked for and showed you the result.

This is in the specification itself: any extra word produces a valid wallet, and only the correct one opens yours. BIP-39.

Before writing off the passphrase, rule out the other cause

"It restored and it's empty" has two common causes, and from the outside they look identical. The other one is the address type: the same seed, with no passphrase at all, opens four different wallets depending on which derivation standard the software uses, and three of the four will show you zero.

Rule that one out first, because it is fixable and a forgotten passphrase usually is not. The difference shows in the prefix of your master public key — xpub, ypub, zpub — which encodes the address type that branch derives.

The ceremony separates the two cases in under two minutes: derive your first address from the public key you wrote down and match it against the one your wallet shows. It runs in your browser, never asks for the seed, and cannot send anything anywhere.

If it was the passphrase

There is no way to recover it from the seed — that is precisely the point of having one. What does sometimes work is rebuilding the context instead of guessing the text.

• Try the obvious variants systematically. Leading capital, a trailing space, an accent present or missing, a different keyboard layout. Write down what you tried: without a record you repeat attempts and skip others.
• Look for where you once typed it. An old password manager, a note in another box, a photo. The passphrase is usually written somewhere other than the seed — which is exactly what separating them is for.
• Check whether the balance appears with no passphrase at all. If it does, there was no passphrase and the problem was something else.

What this problem reveals

If you got this far, your backup was complete and still wasn't enough: a piece of information was missing that nobody told you to write down. That is the general shape of the problem, and the passphrase is only one of its faces.

The others tend to be dependencies: the email that recovers the phone, the phone that recovers everything else, the passphrase that exists only in one person's head. Six questions are enough to map that and find where a single loss locks you out. It asks for no secrets, and it also runs in your browser.