If there is no written contract, employment in the US is at will. For at will employment, there is nothing to prevent an employer from withdrawing an H-1B.
J Charles Ferrari Eng & Nishimura 213.622.2255 The statement above is general in nature and does not constitute legal advice, as not all the facts are known. You should retain an attorney to review all the facts specific to your case in order to receive advise specific to your case. The statement above does not create an attorney/client relationship. Answers on Avvo can only be general ones, as specific answers would require knowledge of all the facts. As such, they may or may not apply to the question.
The company has the right to withdraw the petition at any time. Additionally, the company doesn't have any work for you to do. I'm sorry you're facing this situation. Best of luck to you.
Samuel Anthony (“Tony”) Silva - (901) 278-1004 (office) - email@example.com. This answer is only for general information purposes. It does not establish an attorney-client relationship. The answer I gave is based only on the facts that you have presented in your question and might change if the facts are different.