I opened up firefox to see that all my passwords disappeared, I've tried syncing, and following this article (https://support.mozilla.org/en-US/kb/recover-user-data-missing-after-firefox-update), but still nothing. I can see in my firefox profile file that there are logins.json-4.corrupt files, but I don't know what to do from here. Please can someone help? (Also please be explain step by step simply)