1. if my case denied, am I will be out of status?
If you have left the previous employer, you may be out-of-status based on last action rule.
2. do I have to go back to my native country? if yes then soon
USCIS denial notice usually specifies the duration to leave.
3. should I go back to my previous employer? or find another new employer
Since your I-94 is valid, you may go to your old employer or a new Employer. Since you have joined another Employer, even your OLD employer will have to file a new H1B Extension.
4. what I suppose to do to continue my work in USA
You can legally work as long as the H1B Extension is pending with an Employer for 240 days
Forms Preparation fee for H4 is $95.00, H1B (New/Extension/Transfer, Amendment) is $295.00 (includes Public Access file), H1B/I-140 RFE write-up Starts at $195.00, H4 EAD $95.00 and GREENCARD/PERM/I-140 starts at $500.00, check us out at www.vesaservices.com or email at firstname.lastname@example.org