How to find MetaMask 
Vault Data in computer’s files (guide for Windows users)
if you use a Firefox browser and you can’t open your MetaMask wallet
You need to know the password for your MetaMask wallet
Ways to Find Your Firefox Profile Location in Windows:
about:support
When you open a Firefox Profile folder: xxxxxxxx.default-release 
Open folder storage and in the storage folder 
open the default 
folder.
How to find a MetaMask Internal UUID
about:debugging#/runtime/this-firefox
Now i know 
that my MetaMask folders have a name: feaa69fe-435c-4dc8-8f73-9941fd189f56 your files will have another name.
Open a folder with a longer name
moz-extension+++feaa69fe-435c-4dc8-8f73-9941fd189f56^userContextId=4294967295
In this folder search file with number. My file is 709 this file contains MetaMask vault data.
Download and install EmEditor: https://www.emeditor.com/#download
Right-click on your file and open it in the program EmEditor
Search for words like: Keyr, data, d a t a, salt or s a l t
Text editing 
You have to find something like this:
{“data”:“wwpXXtFCqZkYsWfeEwItZjJ0Cc7mRVjG47Dqh+ztL1PiCG6Izhg+zG0mM+H2ykyjz3X0RNhAE6IVsWFZamcZ47B4sVi4SvUxrMhARm5L3yHPxr3UsyGrOXmthyVMgEGmjwlmnFCNd2nMZ2o8/sRMra8FupurqevnBv57FiYpEEs7gPpFHv6587aL44MmKD8Snv4JLFqiqmlK82Waq5F+Iv9mw2sFVAL9mgZBSgFgbWdB3TsKVB2k”,“iv”:“rkUQlNcGTxBE0My7a/bCXw==”,“salt”:“HcKyNfGzaRALRQ0DlKgcIe5Uk30iI/M//oG6w8vX8Nk=”}
Your data will look like this:
Click Search -► Replace… or use the keyboard shortcut Ctrl + H
According to the picture above 
remove spaces in the text.
Download Vault Decryptor:
https://github.com/MetaMask/vault-decryptor and unzip this file to the your desktop 
Open folder vault-decryptor-master -► and open index.html file in the browser 
Paste the {“data”:} and use the password you set for your wallet in the MetaMask extension and click the “Decrypt” button as shown in the video by MetaMask - Randy
Everything is done 
and now you see your MetaMask seed phrase
PS: If your file contains more special characters as in this picture
You need Ubuntu 21 or another linux system.
How to Install Ubuntu 21 on VirtualBox:
https://www.youtube.com/watch?v=360uNjkiEjY
When you run Ubuntu download and install: Snappy-fox
https://github.com/berdav/snappy-fox
Launch a terminal in the folder snappy-fox:
and write a command: sudo apt install make gcc confirm the installation by pressing Y
Then just compile the application next command: make
Now you see new file with name snappy-fox everything is ready.
Now I’ll move my file 709 to folder snappy-fox
and the last command is: ./snappy-fox 709 709.txt
file 709.txt will be without special characters yeah