Do you have access to an Apple Store? If so, they would have a known good power adapter that you could try. An Apple authorized repair shop might also have one on hand. If you have the problem with a known good battery and a known good power adapter, then there is a problem with the DC In Board.
If you have access to another iBook, you can swap power adaptors and narrow down the possibilities in a similar fashion.
In view of the fact that the problem began after the trip over the power cord, it is likely that damaged the power adaptor tip or the DC In Board or both. The power port is a part of the DC In Board, and fairly vulnerable to damage. It is, however, something you can fix yourself if you like:
http://www.ifixit.com
You can look up the part and see what is involved.
I don't know of any external type charger other than another iBook.
Good luck!