Our doorknob won't open, the lock doesn't unlock and the removal of the knob doesn't help.?

The doorknob lock malfunctioned, the door know wouldn't unlock (the deadbolt is fine), we removed the knob, both exterior and interior, but the internal lock mechanism won't unlock for us to pull the long portion out of the door. There is no hole in the door that would allow us to slide it out. Does anyone have a suggestion on how best to remove the mechanism? Nothing tried seems to work, scredriver to "fiddle" with the mechanism, etc. I'm afraid we'll have to call a locksmith to have it removed, which is an expense we would like to avoid. Thank you