If you are disabled and apply for Social Security, you may be denied the first time.  You then have 60 days to appeal the decision.  You basically cannot work at all during the appeal process.
 If you are turned down, consult with an attorney to see if you need a Representative.  If you are turned down on Reconsideration, it is time to appeal and ask for a Hearing.  It is usually best to have an Attorney appear with you at the Hearing before the Administrative Law Judge.  The Judge decides if you are disabled according to Social Security law.  The attorney can only charge 25% of any back pay you receive.  The Judge has to approve the fee.