Depends on context. Having a nervous breakdown is a non specific label and does not preclude employment. To get disability your mental state must somwhow be connected to the capacity to meet the requirements of your work.
Nervous breakdown. The term nervous breakdown means different things to different people. If a menatl health issue arose from a work related source, you should be evaluated by a mental health professional to see if returning to the job would be prudent. Disability determinations are also done by that type of professional, ie., a psychiatrist.
Need evaluatiiom. Associating work with the onset of your illness makes it tough to go back--disability may make recovery & return to work difficult as well--see a psychiatrist.4 evaluation & recommendations.