This is done as follows:
Go to this page: https://github.com/luigi1111/xmr.llcoins.net/
Click on Clone or download
and download the ZIP file. This ZIP file can be used offline if needed.
In addition, you can verify the files by following the steps in the README: https://github.com/luigi1111/xmr.llcoins.net/#xmrllcoinsnet
Open addresstests.html
Put the 13 word MyMonero seed in box 1. Mnemonic Seed
Click on Gen 2.
Click on Gen 3 & 4.
Click on Gen 5.
Click on Gen 6.
Click on Gen 7.
Now that you have your private view key + private spend key + public address, proceed with this guide:
How to restore a Monero wallet from Private Keys
For the CLI, first perform step 1 to 10 as well. Thereafter, perform the following steps:
[1] Browse to the directory monero-wallet-cli
is located.
[2a] On Windows, open a new command prompt from the same directory as monero-wallet-cli.exe
. This is done by first making sure your cursor isn't located on any of the files and subsequently doing SHIFT + right click. It will give you an option to "Open command window here". If you're using Windows 10, it'll, most likely, give you an option to open the Powershell.
[2b] On Linux and Mac OS X, open a new terminal from the same directory as monero-wallet-cli
[3a] On Windows, type the following command in the command prompt:
monero-wallet-cli.exe --generate-from-keys <wallet-name>
If that doesn't work in the Powershell, type:
.\monero-wallet-cli.exe --generate-from-keys <wallet-name>
If that doesn't work either in the Powershell, type:
./monero-wallet-cli.exe --generate-from-keys <wallet-name>
[3b] On Linux and Mac OS X, type the following command in the terminal:
./monero-wallet-cli --generate-from-keys <wallet-name>
[4] Enter your private spend key, private view key, and public address, and it will "recreate" your MyMonero wallet.
P.S. Luigi1111 is a core-team member of Monero.