No one wants to get sick, to have an accident, to become disabled. But sometimes life happens, and if you become disabled and your disability keeps you from being able to work, you should think about the beginning the process of filing for disability with Social Security.
SSDI is not a government benefit-it's an insurance program, and you pay for that insurance from the payroll taxes you contribute from year to year. Your coverage lapses approximately 5 years after you stop working full-time, basically because by not working you are not paying your premium.
It's important to remember that Social Security Disability is very different from retirement. Your retirement payment is based on your entire work history, while, your SSDI only looks at the prior ten years. Before you file for Social Security disability benefits, you should contact your nearest Social Security office to learn your "date last insured." However, it's much better if you look at your statement yourself without relying on a clerk. Either obtain your statement on-line, or ask the clerk to print your statement out for you, so that you do not have to take the clerk's word as to your date last insured.