If a persons probation has been revoked due to a conviction of a class a misdemeanor assult, what are the chances of having their probation reinstated?

Your question is a bit confusing-- so here are a couple of different responses, depending on the status of where your case is at.

If the probation department has filed a motion to revoke your probation, but you have not been officially revoked by the judge yet-- then you have the potential to have your probation reinstated.  Whether or not your probation will be revoked, depends on the attitude of your judge, your probation officer, and the prosecutor handling your case.  Some consider a misdemeanor charge  an minor "blip" on probation and don't get too stressed about it.  Others consider it a major infraction and will revoke your probation.  So, no one can really give you a guarantee of what will happen.  The fact that it's a misdemeanor helps. The fact that it's an assaultive offense hurts.  You don't have the best chances of reinstatement, but there is still a chance if you can show there were unusual circumstances related to the assault or that you've really taken measures to fix the issues that lead up to the assault.  Many judges and probation officers appreciate defendants that are proactive in addressing their own issues.  To get a better feel for what type of judge you are dealing with, talk to your probation officer.  Also arrange for a consultation with a couple of local defense attorneys.  If you visit with two or three, you should start to get an idea of what is mostly likely to happen in your case.

On the flip side, if the judge has already revoked your probation and has sentenced you to jail or prison time, then your potential for reinstatment is very limited.  If you are on probation for a misdemeanor offense, then you're not going to get reinstatement after a revocation.  If you are on probation for a felony offense and have been sentenced to prison time, you can still make an application for "shock probation."  This is where a defendant is shocked back from prison after they have been sentenced.  They are returned to the court who then places them on a strait probation.  The purpose of the shock probation is to give a defendant a taste of prison life, without the full imposition of sentence, to give them an incentive to not reoffend.  The decision to grant or deny is solely with the judge.