I have only a copy of I-797C, can I use this copy and get the original copy from USCIS?
You may wish to ask for a duplicate approval notice if you have found out that your application or petition has been approved and:
* You need a new copy to replace a lost copy, or
* You never received the original notice of approval.
You must file a Form I-824 (Application for Action on an Approved Application or Petition) with the appropriate fee to get a duplicate approval notice. Your request should be filed at the USCIS office that approved your original application or petition.