Running 2 copies of Audacity

I have been successfully running Audacity for a week. On opening Audacity this morning I have been unable to open any files, receiving the under noted error message. I have closed Audacity/Forced quit and rebooted several times but with the same error message. I am unable to locate this 2nd copy to close it down.
Can you help me with this please.
Thank you.

"Error Locking Temporary Folder
Audacity was not able to lock the temporary files directory.
This folder may be in use by another copy of Audacity.
Running two copies of Audacity simultaneously may cause
data loss or cause your system to crash.

Do you still want to start Audacity?"

See this topic:

Problem sorted.