H1 Extension denied on Apr 6th and i94 denied on sept 20, 2019

Hi, My H1B extension got denied on Apr 6th 2020, i-94 got expired on Sep 20, 2019 already. Is there any possibility to change employer and start work for same client immediately?

No, you cannot do anything as your I-94 expired. You are technically out of status now. You need to depart immediately. Your other option is to apply for B2 and stay until the COVID situation changes. The reason you cannot apply and work is you do not have legal status now with denial and your I-94 expired.

Thanks Kumar, now I have submitted docs to COS fir B2, May get receipt in next week, now is it possible to apply work permit to Canada and travel once restrictions lifted?

You maybe, I am not sure about Canada on what they look for.