As stated above, there are a number of reasons an attorney might withdraw from a case. The most common perhaps is client failure to pay. Also frequent is that the attorney was discharged (or "fired") by his client. Other reasons exist, including an irreconcilable difference of opinion between the attorney and the client as to how to pursue a case, an attorney's unwillingness to further an ongoing wrong (such as a crime or tort), or replacement by another lawyer.
As another commenter stated, there is really no way to know. What we can say is that there probably WAS a good reason; attorneys face ethical charges or possible liability if we withdraw for no good reason, especially when doing so leaves a client scrambling for counsel.
No attorney-client relationship or privilege is formed by this communication. This answer is to be considered as a general discussion of legal principals and is NOT LEGAL ADVICE. If the asker seeks specific legal advice, he should retain an attorney, who will naturally take the time to consider all aspects of the case and perform any necessary legal research.
The attorney-client relationship can be complicated and almost always requires a strong team approach. When that is absent, an attorney may feel ethically obligated to withdraw. And that is only one of the many possible reasons. To anyone other than the attorney and the client, the circumstances can easily remain a mystery. In fact, the caring and knowledgeable attorneys of Avvo don't really know any more about this mystery than do you; we are not clairvoyant.
Best wishes for an outcome you can accept, and please remember to designate a best answer.
This answer is offered as a public service for general information only and may not be relied upon as legal advice.
Just based on your statement, no one who is not involved can tell you what is going on. Your case would have to be looked into and the file reviewed. If there are two wills for the same person, then more than likely a court will determine which one of the wills is the valid will.
Just to add to possible reasons not stated by the other attorney answers, it could be that the attorney is not a litigation attorney and the matter is going from a probate matter to a estate dispute matter. The dispute matter takes different skills and not all probate attorneys have or want to use these skills.