Firefox fails to start

[Broadback]

After a couple of days of good running Firefox now fails to start after switching the machine of. Firefox help suggests:
"To test to see if this is the problem, use the Profile Manager to create a new profile. If the problem goes away, you can then move your bookmarks and other important settings into the new profile."

However I cannot find how to create a new profile, I have tried the way suggested in the Firefox help page but that is a no goer. Can someone please help me to create the new profile in Firefox?
TIA

[Simon]

Does this help?

http://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles

[Broadback]

I'm afraid not Simon, that was the one I could not get to work/follow. 

[Simon]

If you can find Firefox in your All Programs list, there may be other options there, such as starting Firefox in safe mode, or accessing Profile Manager.  It's possible that an add-on might be stopping it from starting.  Have you tried re-installing it over the top of itself?

[Broadback]

The only way I can get it to work is deleting then re-installing, if I re-install over iself the problem persists. However I have now reset Firefox to its default stage via the trouble shooting option. Now it reloads ok after switching off. I hope it lasts, only time will tell. It's a good job I am retired, I have spent hours on this computer of late! 

[pctech]

Its likely an add-on will have destabilised the install, had there been a problem with the main application I doubt it would have started in safe mode.