From MozillaZine Knowledge Base

Suddenly I was asked to choose a start-up profile for firefox. Only one was listed; the default one which I have used all along and adapted to my needs. When I tried to choose that one, I was told it was allready in use, so I created a new one and chose that.

when firefox opened, all my settings where gone, and I can not find out how to change profile back to the one I had before.

How can this be changed?