How to Reset Mozilla Firefox when it does not Open

Learn the steps to reset Mozilla® Firefox browser when it is not opening. Resetting Mozilla Firefox to its Factory settings or default settings can fix the most common problems.

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[mamawlies]

That window won't even pop up when I shift click.

[kevinhall]

After watching couple of videos I found Yours videos And really

Helped me a lot

[troncharles]

when i i hold shift and click it  nothing happens wont open

[gopdeep]

I can not sing in in youtube Firefox .. I get message when I click sign in We've detected a problem with your cookie settings... Please help me

[anitakatherine]

I have Windows 7 and no box pops up to reset. only the original error box that platform version is not compatible with minversion.  Help!

[_reynero_]

Thanks bro, it works
Now Firefox is working without error

[Mac-oxow]

I cant open "Safemode" I forgot my password because I just had it saved is there anyway I can type in my Microsoft password and stuff so I can view my old saved passwords?

[SundarKuppan]

SHIFT + click works for me and refresh window opens. Before trying to reset close Firefox if it is running in the background from task manager and see if it works. That is how it worked for me.

[KKCT]

I get nothing when I click Firefox - nothing opens when it previously opened - what's going on?
I tried update - didn't work
I tried System Restore - didn't work
I tried Firefox while holding "Shift" down - didn't work (no pop-up window)
I tried uninstalling Firefox and installing from the Firefox website - didn't work
I started in Safe Mode - same thing, it didn't work...

So, when I say 'didn't work' I mean I double-click the Firefox icon and the little hourglass icon appears for a second or two before it disappears again but Firefox doesn't open. This has happened each time I tried one of the above solutions. Firefox was working perfectly before I went on vacation a couple weeks ago. Since I returned, and turned on my pc, it refuses to open.

Wits-end.

[RickHeilmanPeacewarrior]

Thanks...I did not get the reset Firefox, but it opened up 3 tabs and finally let me in to Firefox.

[davidbeach]

Did what you told me to do, and it did not open anything, a very disappointing experience for me sadly .

[sammywoof]

how about when you start to open internet explore, "it says the instruction at 0x70638bc referenced memory at The memory could not be read.
Click on OK to terminate the program."
What should I do

[kiyaswan]

Thank So clear, so easy, and it worked! <3

[donriddick]

This worked for me on win 10 man thanks

[sangmouass]

in programs, I click Mozilla and it don't do anything..cant even get to the reset button part. any ideas. it just will not open

[robincainking]

Will I lose my preset tabs if i reset firefox?

[ecouturehandmades]

No, trying to get Firefox to open in Safe Mode did not work either. System Restore may have been what got me  back online by going back three weeks or so, to BEFORE downloading that ''Safe'' version of Firefox. Or before even getting the notice the a 'new version' was available to download!
Since Firefox has become the only available working browser that will open on my very old computer, and there is no way for me to afford a new, or newer, computer (and it cannot be upgraded any further), I  fear the future.
Your videos, while very ''pretty'', aren't all that helpful. You are assuming everyone has a built in 'reset' button, which would probably be part of a W8 system or better, but there are still many of us struggling along with outdated equipment that gets 'killed' by 'upgrades' that we mistakenly trust, because they come from the manufacturer. 'Planned Obsolesence'? Certainly! 
At least I am not on 'dial up'.

Oh yes, thank you for getting back to me to find out whether your suggestion had worked. So timely.

[Myreverlation]

HELP This Didnt Work... When I Did It It Still Wouldn't Open It Keeps Saying .  
COUlD NOT FIND THE MONZILLA RUNTIME
Help Me Please

[sangmouass]

I tried didn't work, tried control-shift and it asks me to run it, when I click yes.it does nothing. any other thoughts on this?

[ecouturehandmades]

These hints are not working for me. I have an old system running WinXP2 (cannot upgrade). Firefox very recently upgraded to 38.0.5(?) and now refuses to open. Start, programs shift and click on the mf progrm result in nothing - no pop up window, no regular window, just a quick flicker of the hourglass, then no response. I also tried system restore with no results. I cannot delete firefox, as it is the only browser that works on this computer (Chrome is no longer supported). HELP!! All of my life is on this computer. I can access all my files, but not the outside world.