What can I do to receive the bonus check that I earned?

A critical issue, though, is whether the bonus *was* earned or was discretionary. An earned bonus is one an employee gets because he or she achieved certain previously defined targets or goals, such as a sales rep hitting sales targets. If there were targets or goals in place and the employee achieved them, then he or she did earn the bonus and is entitled to be paid it; if the employer doesn't pay, the employee may take legal action or file a complaint with the labor department.
However, a discretionary bonus is one where the employer simply chose to give an employee a bonus without the employee having accomplished previously defined goals. A discretionary bonus is, as the term implies, at the discretion of the employer: the employer freely chooses to reward certain employees--and may equally freely choose to *not* reward them, even after having first told the employee that he/she would get a bonus. The employer may freely renege on a promised discretionary bonus, so if this was a discretionary bonus, you would almost certainly have no legal recourse.

You can do a couple of different things.  One is to contact the Texas Workforce Commission.  They not only help with people who are unemployed, but they also help enforce the pay day laws of Texas, which require an employer to pay any amounts that they have already earned.  A copy of the stub will be evidence that the bonus was already earned.
A second option is to contact the HR department and dispute the termination or the non-payment.  Some medium to larger companies have procedures for this --- and HR may not have been aware that some manager was subjecting the company to potential liability for non-payment. 
A third option is to hire an attorney for the simple task of writing a demand letter requesting payment of the bonus.  If your employer still refuses, then the attorney can advise you of the actions from that point.