Well hope you did not want anything in your profile as probably gone now. https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data . https://support.mozilla.org/en-US/kb/export-firefox-bookmarks-to-backup-or-transfer and https://support.mozilla.org/en-US/kb/import-bookmarks-html-file . https://support.mozilla.org/en-US/kb/recover-lost-or-missing-bookmarks . https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles , https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile . https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles This is the best way to uninstall Firefox. Then Delete the Mozilla Firefox Folders in C:\Program Files and C:\Program Files(x86) Then restart system. Then run Windows Disk Cleanup. Then run it again and click the button that says Cleanup System Files. Note: your Firefox Profile is saved. But you should make a back up before you do : https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles If nothing recoverable from your Profile then delete that folder also. Reinstall with Current Release Firefox 57.0 with a Full Version Installer https://www.mozilla.org/firefox/all/ Please let us know if this solved your issue or if need further assistance. .

Didn’t help, tried it again but still broken. Any way I can get mozzilla to teamviewer into my pc or something equivalent?

Any other ideas anyone? Not fussed about loosing my local stuff as it’s all backed up on my firefox account.

Try to update to Firefox 57.0.1. *Help -> About Firefox

Thanks cor-el! Updated and it worked, then signed into my sync and everything came back. Can’t thank you enough!

Try to update to Firefox 57.0.1 to see if that version fixes it for you. *Help -> About Firefox