Courtesy of HowtoGeek:
Want to reset your web browser to its default settings? You can’t necessarily just uninstall it — your personal files will stay on your computer. And if your browser is Internet Explorer, it can’t be uninstalled at all.
Resetting your browser to its default state can often fix problems. For example, a program you install may change your search engine, install toolbars, and do other unwelcome things. Or you may have accidentally changed advanced settings on your own.
Google Chrome has an option that will reset itself to its default settings. To find this option, open Chrome’s menu and select Settings. Perform a search for “reset browser” and you’ll see the Reset browser settings button.
You could also just plug chrome://settings/resetProfileSettings into Chrome’s address bar to pull up this page.
Use this option and Google Chrome will erase almost everything — your extensions, settings, cookies, history, home page, default search engine, and more. Chrome won’t delete your bookmarks or passwords, so your important personal data will be kept.
Learn more about troubleshooting Google Chrome crashes if this didn’t solve your problem.
Firefox also allows you to return it to its default state. To do so, click the Firefox menu button, point to Help, and select Troubleshooting Information.
Click the Reset Firefox button on the Troubleshooting Information page.
Firefox will erase your extensions and themes, browser preferences, search engines, site-specific preferences, and other browser settings. However, Firefox will attempt to preserve your bookmarks, history, passwords, form history, and cookies.
The Reset feature accomplishes this by creating a new profile for you, copying this important data over. Your old profile will be placed on the desktop in a folder titled “Old Firefox Data.” If you lose important data in the reset, you can attempt to recover it from this folder. If you don’t need the folder, you’re free to delete it.
Consult our guide to troubleshooting Firefox crashes for more information.
The desktop version of Internet Explorer has the ability to reset its settings to the default ones. If you’re using Windows 8, resetting Internet Explorer on the desktop will also reset Modern Internet Explorer’s settings.
To do this, open the Internet Explorer desktop app, click the gear menu, and select Internet options.
Click over to the Advanced tab and click the Reset button at the bottom of the Internet Options window. Internet Explorer warns you that “You should only use this if your browser is in an unusable state,” but that’s just to dissuade you from wiping out all your personal settings unless it’s absolutely necessary.
Internet Explorer will disable browser add-ons and erase browser, privacy, security, and pop-up settings. If you also want to reset your home page and search providers, as well as delete temporary files, history entries, and cookies, check the Delete personal settings box.
Your favorites and feeds won’t be erased. However, passwords you’ve saved in Internet Explorer will be deleted.
After resetting Internet Explorer, you’ll have to restart your computer for your changes to take effect.
Read more about troubleshooting Internet Explorer crashes if you still experience problems.
Safari has no built-in feature that resets itself to its default state. You can click the Safari menu and select Reset Safari, although this will only delete your browsing data — not reset Safari’s browser settings to their defaults. You’d have to delete Safari’s configuration files by hand to entirely reset Safari.