Hi, in case you activated some Windows 7 feature, could you do a regular shutdown/restart of Windows? Hopefully that will revert any temporary changes.

If your Firefox is ignoring the Backspace key, instead of going Back like the Back button on the toolbar, here is how you can fix that:

(1) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button accepting the risk.

More info on about:config: Configuration Editor for Firefox. The moderators would like us to remind you that changes made through this back door aren't fully supported and aren't guaranteed to continue working in the future.

(2) In the search box in the page, type or paste browser.backspace_action and pause while the list is filtered

(3) Double-click the preference to display an editing field, and change the value to 0 then press Enter or click the blue check mark button to save the change.

Any improvement?

If you still want to start over with default settings, this article has more information: Refresh Firefox - reset add-ons and settings.

I got the back function to work again. Then I found out that the textmarker function was enabled. So I disabled that too. Thats why I would like to reset to state.

I did the firefox recovery. But that didnt help me

What is the textmarker function? Is that "caret browsing" where a vertical bar moves through the page? You can try the F7 key to toggle that off or, on the Settings page, uncheck the box for "Always use the cursor keys to navigate within pages".

Yes its the caret browsing. I have make it function again.

But I would like to reset all settings to its state.

Because I could made change of settings for other things as well

Usually a Refresh/Reset gives you fresh settings with only your bookmarks, history, and saved logins carried over. If you want an even cleaner start:

Inside Firefox, type or paste about:profiles in the address bar and press Enter/Return to load it.

Click the "Create a New Profile" button, then click Next. Assign a name like March2024, ignore the option to relocate the profile folder, and click the Finish button.

Scroll down to March2024 and click its Launch profile in new browser button.

Firefox should open a new window that looks like a brand new, uncustomized installation. (Your existing Firefox window(s) should not be affected.) To recover some of your data, you can connect to your Mozilla (Sync) account.

Meanwhile, you can close the other window.

Ok. All I want is to go back to an installation of firefox without having firefox before.

So everything is turned to state/standard

I will make this a chance. But I would like to have the download history, bookmarks, search history in the new profile