Firefox Already Running Error Conflict

Hi to all Firefox gurus,
I am here with a small problem occurring with my Firefox browser.
Firefox is already running, but is not responding. To open a new window, you must first close the existing Firefox process, or restart your system.
I was using Firefox at that time I got a surge attack to my Computer because of which my computer restarted and when it turned on I double clicked the firefox.exe shortcut icon to run it but it gave me this error message that Firefox is already running, but I don’t see any Firefox page opened on my desktop then why do I receive this error message.
I thought that it may be due to some other program conflict so I closed all other programs opened but still I was receiving the same error.
Could anyone please tell me how to get rid of this error?
