I use this Pidgin on Windows 7. After removing an entire folder of Pidgin to another location I can't access my acounts. When I run Pidgin the welcome window will always appears. Of course, I've got a purple folder in Pidgin. Don't you happen to know where is the problem?
Move it back to where it was and run it again. A good percentage of portable apps will partially or completely break if you change their path. Portable apps are made to have their drive letter change.
Sometimes, the impossible can become possible, if you're awesome!
I backed up the purple folder and then deleted it in Pidgin. Then I put the backed up purple folder back into Pidgin. And now it works. Maybe it was just an accident.