If you cannot perform the duties of your job even with an accommodation, your employer can generally fire you. The protections of the ADA only apply to individuals who can perform the duties of their job, with or without an accommodation.
If you cannot perform the duties of your job, then you should carefully review your company’s short term and long term disability plans. Please be aware that employers are not required by law to have long term disability plans and that many employers do not have them, says a NY state disability lawyer.