Reversion to parent post

Hi, I had appointed as a Medical Lab technician in 2008, in Ordnance factory medak, which is under ministry of defense. the post is under Non-Industrial employee category. the Grade pay 2800. But later in 2014 after principal bench order implented upgraded to Grade pay 4200. In 2012 through LDCE I became Group "B" Non-Gazetted Officer [NGO]. in the same department , after filling the post I got relieved to the other concerned section. But due to some occupational hearing problem now I am not able to continue in the same technical post and planning to submit my application to get revert back to parent post..But now the post is allready filled. please help any one in this matter ....how to proceed. and get parent post back.... hope a positive reply from our respected esteemed and brave members please. IN RESPONSE TO MY APPLICATION THEY GAVE SIMPLE REPLY REGRETTED BY COMPTENT AUTHORITY. [deleted] [deleted]