Could you provide more details about what happens when you try to install Firefox?

If the installer you downloaded has "stub" in its name, try downloading a "full" or "offline" installer from this page (scroll down to your preferred language):

https://www.mozilla.org/firefox/all/

Choose the "Windows" version (32-bit) rather than the 64-bit version for maximum plugin compatibility (and of course for 32-bit Windows systems).

THis is the Error message i get.

Your Firefox profile cannot be loaded. It may be missing or inaccessible.

You shouldn't get that message on a brand new installation that completed normally. Did you already have Firefox installed?

If it's a new installation, please create a new profile by starting Firefox up in the Profile Manager. This article has the steps for that: Profile Manager - Create, remove or switch Firefox profiles.

Once you start up in the new profile, you can import data from your existing browsers. See: Import data from another browser.

Success?

i've tried suggestions above....still same issue....getting pretty irritated now.

In the profile manager, you created a new profile, then selected that profile and told Firefox to start up in that profile, and it didn't work?

If you have not restarted Windows since this problem began, please shut down and restart Windows in case there are deferred file updates or permission issues.

still did not work.......i'm fed up

I've never heard of anyone who created a new profile getting the error message starting up in that new profile. Your Firefox installation may be damaged. Could you try this next:

Clean Reinstall

We use this name, but it's not about removing your settings, it's about making sure the program files are clean (no inconsistent or alien code files). As described below, this process does not disturb your existing settings. You do not need to uninstall Firefox first.

It only takes a few minutes.

(A) Download a fresh installer for Firefox 50.0 from https://www.mozilla.org/firefox/all/ to a convenient location. (Scroll down to your preferred language.) Choose the "Windows" version (32-bit) rather than the 64-bit version for maximum plugin compatibility (and of course for 32-bit Windows systems).

(B) Exit out of Firefox (if applicable).

(C) Using Windows Explorer/My Computer, rename the program folder as follows:

32-bit Firefox on 64-bit Windows: Rename

C:\Program Files (x86)\Mozilla Firefox

to

C:\Program Files (x86)\OldFirefox

Other combinations: Rename

C:\Program Files\Mozilla Firefox

to

C:\Program Files\OldFirefox

(D) Run the installer you downloaded in step (A). It should automatically connect to your existing settings -- which may or may not be found.

Note: Some plugins may exist only in that OldFirefox folder. If something essential is missing, look in these folders:

• \OldFirefox\Plugins
• \OldFirefox\browser\plugins

If Firefox 50 can't start because it can't find your profile, try the Profile Manager again.