You don't provide enough facts for a proper analysis. If you were an at-will employee, your employer may legally fire you for any reason as long as it is not based on a protected class (age over 40, gender, race, religion, medical condition, etc.) or because you were a true whistle blower - which means that you complained about violations of the law by your employer or because you asserted your legal rights (example: overtime pay.) An employer may accept a resignation at any time and even if it was withdrawn by you, they can legally fire you for any lawful reason. Violations of the employer's handbook do not lead to a viable lawsuit unless the violation is one of a law. I find that whenever I or any firm, large or small, rejects a case, it is because the case is not very good. A big firm can always find time to take a case of an individual. If you believe you were fired because of any of the reasons stated above, call an employment law attorney to discuss the facts.