Hello yashduggal, and thank you for your question.
If you've placed Magento in maintenance mode, and it seems to be stuck in this mode. You should be able to connect to the server with FTP, then look in your Magento installation directory for the following file:
If you go ahead and delete that, it should allow you to regain access to your Magento website once again.
If that still doesn't allow you access. I have seen it before where Magento tries to put your normal files back in place, and in doing so, it changes their permissions to  which means they're writeable to the world and this causes a suPHP permissions error.
If this is the case, you should be able to change the file permissions so that they are  for all your files and that should hopefully do the trick.
If you're still having any problems at all please let us know!