What sort of collar do you use? Maybe she is not used to the sort you are using, or maybe she had a harness before.
You could try taking her somewhere by car and then trying to get her to walk home (obviously not too far!). Have you tried using food or her favourite titbit to encourage her. You could also try getting someone else to hold her lead and you walk in front calling her to you. If you have a garden or access to a field try letting her loose with a lead attached and let her trail it about a bit, then try to pick the lead up without her noticing and just follow her round holding it for a while.