Hi Suman ,
In T code SM 58 you will find the Shopping cart items got blocked, try to reprocess the blocked shopping cart, follow on documents will be created.
If you face still issue execute txn SE37 and enter BBP_REQREQ_RESUBMIT and then execute. Enter the shopping cart number in REQNO field and then execute the Function Module.
I hope it will be help full for you.
Regards,
Pradeep Kumar Dondeti