MetaMask – How to Restore Account Information Using Seed Words?

you can't get it.

You didn't get any seed because the accounts created with geth aren't part of a Herarchical Deterministic Wallet.

The seed is a 12-word composition called mnemonic, which is derivated via HMA-SHA512, in order to obtein all the accounts of a (HDW).

By creating accounts with geth you'll never be able to get a seed, because the accounts don't come from it.

Anyways, you can import your account into Metamask as said on this post response:

You can now import single/"loose"(as we call) keys into MetaMask if you click the menu in the top right corner. It will drop down with the option "Import account", you can click that and it will take you to a view where it will ask you to import your private key or json file.

Hope it helps.

If you were using the Google Chrome browser in Windows 10, you should be able to find the location of the Vault by going to this folder location (you need to be able to see the hidden files):

C:\Users\USER_NAME\AppData\Local\Google\Chrome\User Data\Default\Local Extension Settings\nkbihfbeogaeaoehlefnkodbefgpgknn

In that folder you'll see a file called 000003 (or something like that), open that file with a text editor or code editor software like Atom (https://atom.io/).

In the text editor search for the word "vault" and copy this part that looks like the one pasted below:

{"vault":"{\"data\":\"wwpXXtFCqZkYsWfeEwItZjJ0Cc7mRVjG47Dqh+ztL1PiCG6Izhg+zG0mM+H2ykyjz3X0RNhAE6IVsWFZamcZ47B4sVi4SvUxrMhARm5L3yHPxr3UsyGrOXmthyVMgEGmjwlmnFCNd2nMZ2o8/sRMra8FupurqevnBv57FiYpEEs7gPpFHv6587aL44MmKD8Snv4JLFqiqmlK82Waq5F+Iv9mw2sFVAL9mgZBSgFgbWdB3TsKVB2k\",\"iv\":\"rkUQlNcGTxBE0My7a/bCXw==\",\"salt\":\"HcKyNfGzaRALRQ0DlKgcIe5Uk30iI/M//oG6w8vX8Nk=\"}"}

Remove the two parts in bold. Now use the Search and Replace feature of the editor to change all the \" to "

You would now have something like this:

{"data":"wwpXXtFCqZkYsWfeEwItZjJ0Cc7mRVjG47Dqh+ztL1PiCG6Izhg+zG0mM+H2ykyjz3X0RNhAE6IVsWFZamcZ47B4sVi4SvUxrMhARm5L3yHPxr3UsyGrOXmthyVMgEGmjwlmnFCNd2nMZ2o8/sRMra8FupurqevnBv57FiYpEEs7gPpFHv6587aL44MmKD8Snv4JLFqiqmlK82Waq5F+Iv9mw2sFVAL9mgZBSgFgbWdB3TsKVB2k","iv":"rkUQlNcGTxBE0My7a/bCXw==","salt":"HcKyNfGzaRALRQ0DlKgcIe5Uk30iI/M//oG6w8vX8Nk="}

You can now go to the Vault Decryptor https://metamask.github.io/vault-decryptor/ and paste that in the textfield there, enter the password you set for the extension when you created your MetaMask wallet. You should be able to see your seed phrase and any manually imported private key below if you click the Decrypt button.