What legal recourse does one have for being unjustly fired from a job?
The company that I worked was told by the estranged wife of a recently laid-off employee that he had made copies of company documents for his own personal use. As the manager of the site, the company then terminated my employment and that a others. They attempted to block the severance packages of several other former employees that had been laid-off weeks before. At the time of my termination I was given no reason for my dismissal. Upon filing for unemployment, the company tried to deny my benefits saying I had been fired. TX heard my case and found in my favor.
Unless you had a written employment contract with the company, you have no grounds for a lawsuit here. You were an employee "at will," and the company does not need to have any reason at all to let you go. They did not need to give you a reason, and they would almost certainly be able to have your wrongful dismissal suit, were you to file one, dismissed very quickly, and certainly before trial. Unsubstantiated allegations or suspicions, as in your case, are more than enough for the company's side.
There are two types of exceptional situations that can lead to a different result. One of these has to do with illegal motives, such as illegal discrimination (race, disability, etc.) or retaliation (such as for filing a workers compensation claim); you haven't suggested anything of the sort. The other is where the company has written policies or an employee handbook, that talk about termination procedure in a way that can be used as contractually binding on the company. This is exceedingly rare, as it only can happen if fairly specific wording is used, and company lawyers now know enough to avoid that.