Create a new clean profile. This will leave the old profile available for later. As to add-ons, always set the Add-ons Manager to check for updates. When you are ready, go to the Mozilla Add-ons Web Page {web link} (There’s a lot of good stuff here) and search for what you want.

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

Ok, but that doesn't really get to it - is there any way I can just uninstall completely and start new?

When you uninstall, does it give the option to remove your personal data? That erases your settings folder with bookmarks, add-ons, etc.

Note that add-ons installed by other software (including plugins like Flash and extensions like the Norton Toolbar) are generally not in your settings folder and will not be removed by uninstalling Firefox.

If you are trying to rid yourself of malware toolbars, if you haven't fully cleaned out your system, they may be reinjected post reinstallation. Here's my suggested procedure for tracking down and cleaning up bad add-ons. I know it seems long, but it's not that bad.

(1) Open the Windows Control Panel, Uninstall a Program. After the list loads, click the "Installed on" column heading to group the infections, I mean, additions, by date. This can help in smoking out undisclosed bundle items that snuck in with some software you agreed to install. Be suspicious of everything you do not recognize/remember, as malware often uses important or innocent sounding names to discourage you from removing it. Take out as much trash as possible here.

(2) Open Firefox's Add-ons page using either:

• Ctrl+Shift+a
• "3-bar" menu button (or Tools menu) > Add-ons
• in the Windows "Run" dialog, type or paste
  firefox.exe "about:addons"

In the left column, click Plugins. Set nonessential and unrecognized plugins to "Never Activate".

In the left column, click Extensions. Then, if in doubt, disable (or Remove, if possible) unrecognized and unwanted extensions.

Often a link will appear above at least one disabled extension to restart Firefox. You can complete your work on the tab and click one of the links as the last step.

Any improvement?

(3) You can search for remaining issues with the scanning/cleaning tools listed in our support article: Troubleshoot Firefox issues caused by malware. These on-demand scanners are free and take considerable time to run. If they finish quickly and especially if they require payment, you may have a serious infection. I suggest the specialized forums listed in the article in that case.

Success?

See also:

• http://kb.mozillazine.org/Uninstalling_Firefox
• https://support.mozilla.org/kb/Uninstalling+Firefox