BREACH OF CONTRACT
In Arizona, because most employment is "at-will", an employee will only have a "breach of contract" claim for termination of employment in limited circumstances. The most common example is if you have a contract with your employer to be employed for an agreed-to amount of time (ex. your employer promised to employ you for one year) but your employer fired you early and without cause under the contract. Absent such an agreement as to the duration of employment, simply terminating your employment likely does not amount to a breach. "At-will" generally means the employer and employee are free to end the employment relationship at any time and for any legal reason.
Nonetheless, if your employment agreement guaranteed other compensation and benefits, there may still be legal claims that can be brought against the employer for not honoring the agreed-to employment terms. For example, if you were promised a sales commission in a employment agreement, and you performed and earned the sales commission based upon that expectation of payment, your employer cannot retroactively decide not to pay you. Or, if your employer promised you certain benefits in exchange for your labor, but then reneged on its promise.
Additionally, even if you did not have an employment agreement, and therefore do not have a "breach of contract" claim, a termination could still be illegal for other reasons (discrimination, retaliation, whistle-blowing, etc.). If you believe you may have been terminated for an illegal reason, you should contact an Arizona employment attorney.