In general, most employees are considered at-will and can be terminated immediately for any reason, or no reason at all, unless there is a written employment contract in place specifying that the employee can only be terminated for cause. Sometimes "cause" is defined, sometimes not, but generally would include circumstances such as failure to meet the job qualifications, misconduct, etc. However, it is illegal to deny employment on the basis of a protected class (like race, gender, religious beliefs, etc.)
I suggest you contact an attorney to determine your legal options. You can find an attorney through the locator service on LawInfo’s home page at:
http://www.lawinfo.com/.
You can also browse through the information in LawInfo’s Free Legal Resource Center here:
http://www.lawinfo.com/consumer.html.