basially, you have to do it yourself.
you can go to ICA and cancel your student pass, and meantime, you will get the temp EP to provide your leagally stay in Singaproe
you can contact Registry Office ASAP to ask suggestion from them, and
go to your department and school to convert back to full-time student, if possible. good luck. I think they will know how to help you. Because i have the same experience with you, and understand the pain. Good luck to you, and hope you can find a job as fast as possible