Have you tried reinstalling it?

Oh,@Lomi491, it is a pre-installed app.

What's your computer system?

Please explain the problem in detail. What happens? What is/are the exact error message(s) ?

Oh, FredMcd, my computer is Acer aspire 5, and the system is intel core i5 10th gen. It did not have an error message, but it only cannot open. It failed to open Firefox.

I am using Google to asking question now

Google is a search engine and a website. Not a browser. Are you saying that when you click on the Firefox icon, the Google page comes up?

https://support.mozilla.org/en-US/kb/how-to-set-the-home-page

Oh, FredMcd, I said that when I click the Firefox app, It did not open. Firefox is an app. I use Google and use this website to ask a question. https://support.mozilla.org/

And, FredMcd Google=Google Chrome. Not a website. It is an app.

So when you click Firefox, Google Chrome comes up? Or no reaction at all?

Let’s do a full clean re-install;

Note: Firefox comes in three or more folders on all computers. They are;

Maintenance: (Programs Folder) <Windows Only> Firefox itself: (Programs Folder) And two folders in the profile of each user on the computer for each Firefox profile for that user.

If you remove the Firefox folder, the user profiles would not be affected.

Download Firefox For All languages And Systems {web link}

Firefox ESR; Extended Support Release {web link}

Beta, Developer, Nightly versions https://www.mozilla.org/en-US/firefox/channel/desktop/

Install Older Version Of Firefox {web link}

Save the file. Then Close Firefox.

Using your file browser, open the Programs Folder on your computer.

Windows: C:\Program Files C:\Program Files (x86) Note: Check Both Folders

Mac: Open the "Applications" folder. https://support.mozilla.org/en-US/kb/how-download-and-install-firefox-mac

Linux: Check your user manual. If you installed Firefox with the distro-based package manager, you should use the same way to uninstall it. See Install Firefox on Linux; https://support.mozilla.org/en-US/kb/install-firefox-linux

If you downloaded and installed the binary package from the Firefox download page, simply remove the folder Firefox in your home directory. http://www.mozilla.org/firefox#desktop ++++++++++++++++++++++++++++ Look for, and remove any Mozilla or Firefox program folders. Do not remove the Mozilla Thunderbird folder if there is one.

Do Not remove any profile folders.

After rebooting the computer, run a registry scanner if you have one. Then run the installer. +++++++++++++++++++++++++++ If there is a problem, start your Computer in safe mode and try again.

How to Start all Computers in Safe Mode; {web link} Free Online Encyclopedia

Oh, FredMcD.I think Firefox is a pre-installed app. And what I said is when I click the Firefox, it did not have some reaction at all. I want to ask about if the app is pre-installed, is I can uninstall it and install again? It will accrue some error?

Read and follow the directions posted above.

It pre-installed

Thank gratefully FredMcD and Lomi491, all look great now. My Firefox can start now. I re-installed it and it looks great.

Glad to help. Safe Surfing.