Re-entry from Mexico via Land NO I-94 given

Please help me, I have a urgentyet wierd problem.
I Re-entered From Mexico via land via car. I was on visa in US but re-entered on B1 when I returned from Mexico. Basically it was an exit and entry to change my visa type.
But at the POE the official didn’t stamp my passport and my I-94 is not generated on checking Online.
I read somewhere that on entry by land a paper I-94 is given,but I wasn’t given anything.
Can you please tell me how I retrieve the latest I-94 reflecting this latest entry.
I don’t even know until when my departure date in U.S. is?
Also, I need to submit this to my employer. Awaiting your response

When you are reentering, did you go to a USCIS office infront of the entry gate? you need to pay some fee and get visa a stamping of status/class of entry into your passport and that triggers an I-94. If none is done above, you might have missed that part which is not triggering your I-94. If you have paid fees, take that receipt OR your credit card statement copy or some similar evidence and write to USCIS ASAP