Hi, You can consider the [https://support.mozilla.org/en-US/kb/reset-firefox-easily-fix-most-problems Reset Firefox] feature via '''Help''' ('''Alt''' + '''H''') > '''Troubleshooting Information'''. (To revert to the previous profile you were using, close the new profile (i.e. exit Firefox), start Firefox and choose the '''Default User''' profile. While the [https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles Profile Manager] is open, you can also delete the newly reset profile (the one containing random numbers), or the former profile, as the case may be). If the reset is okay, it would be a good idea to delete the old profile as it would be left intact with the data until deleted. [https://support.mozilla.org/en-US/kb/Managing-profiles Managing profiles] [https://support.mozilla.org/en-US/kb/Profiles?s=profile&r=2&e=sph&as=s Profiles Howto] If you have security software (antivirus, firewall etc.) installed, you can try deleting all existing instances of Firefox and its related files in all the different configuration areas/modules of the security software. Instead create new allow/trusted rules for Firefox + its related processes. Even otherwise the security software may also ask again when Firefox is started and you can try to allow/trust at that time. Please see [https://support.mozilla.org/en-US/kb/Firewalls this]. [http://kb.mozillazine.org/Firewalls AV/Firewalls Configuration]

Which solutions did you try? Which security software (firewall, anti-virus) do you have? Some security software does have virtualization features that can cause problems by protecting and restoring files in the Firefox profile folder.