Can I continue working after my OPT STEM Extension has been denied?

[renegades90]

I have applied for OPT STEM Extension in December with Employer A. I have moved to Employer B in January and updated USCIS with the New OPT STEM I-20 and I-983. I now have received a denial for my Form I-765 with an update saying that the reason would be sent my mail.Although My VISA is valid until November 2019. Kindly please answer my questions.
1. What is my Current Status now?
2. In such situations, when does the SEVIS get terminated?
3. Is there any grace period to transfer to another University and continue working with my Current Employer? 
4. When is the best time to inform the Employer about my situation? 
5. For Reinstatement as an F-1 Student, do I have to leave the Country?

Any help is much appreciated.

Thanks