Was this a brand new installation of Firefox?

If yes: It sounds as though your default settings folder either was not created successfully or a different Firefox settings file is missing. I suggest running the installer again to see whether it finishes the job the second time. If you downloaded the "stub" installer (the standard one), it might be more efficient and/or less problematic to download the full installer from this page (scroll down to your preferred language): https://www.mozilla.org/firefox/all/

If you already had Firefox, or if the above does not work, please see this help article: How to run Firefox when your profile is missing or inaccessible.

no, this Is a secondary installation of firefox but all old firefox files were deleted

Elijahbiker said

no, this Is a secondary installation of firefox but all old firefox files were deleted

Perhaps the profiles.ini file survived and is causing this error? Either way, please use the steps in How to run Firefox when your profile is missing or inaccessible and see whether that works.

tried and it didnt work, but I was able to locate my past profile

Does that mean you solved the problem already, or you need Firefox to recognize and use the old profile now?

I'm trying to make it recognize the old account

In the article, try the steps for "Profile was moved or renamed" to see whether that connects Firefox to your old profile. If it's in a strange location, it would be best to move it back to the normal Profiles folder:

C:\Users\username\AppData\Roaming\Mozilla\Firefox\Profiles

Currently it is in the proper profile location