lost I797B after H1B visa stamping completed


I lost my I797B form but H1 stamping is completed. Can some one tell, how can I get the duplicate form.
I am in US with H4 visa, do I need I797Bform for H1 transfer?

Thanks in advance.

There is a fee to be paid and I797 to be requested on a form.

You need atlease receipt number.