Made assumption that you are thinking solar system objects as compared to say Earth orbiting or binary stars.
Did find:
http://www.ara.roma.it/MACE/Baer/CODES.pdf which has links to code. Have not used so can not say much about it personally.
There is also:
http://www.projectpluto.com/find_orb.htm
A trip to the library for some celestial mechanics books - there are some good ones with Year 12 to 1st Year uni maths that should cover things - you get to like matrices.
There are also some old(?) books which have computer code for calculating orbits etc. Astronomy with a micro computer and other such title types should narrow the search.