H4-H1-H4 change of status and stamping

Hello, I have stamped h4 visa till Jan 2020. One company applied my h1 b (cos h4 to h1). Which was approved in April 2019.However due to ramp down they never processed my payroll and now they are withdrawing the h1 petition. My question 1).is can I step out of the county and come back on my h4 stamped visa or do I have to take consulates appointment for interview ?
2). Am I Dropbox eligible as I got my h4 visa stamped in dec 2018?

During the period from your H1 petition approval till you switch back to a valid H4 status, you will be deemed to be OUT OF STATUS(aka illegal if you live inside USA during that time).
Having said that, your best option should be going out of the country and enter back using H4 visa.
You may need to go to the consulate appointment for this H4 Visa as you are officially on H1 status curretnly in the books if USCIS.

Hi I stepped out of country and went to Canada and came back to US. Got paper i94 valid till 2020.do I need to worry about my status now?

Yes, you are legal from the date of your re-entry with the status of the visa category (H1/H4) that you have entered with. You dont need to worry in this case.