Try the steps below.
Hope it helps :)
1)Sign in to Gmail.
2)Click Trash along the left side of any Gmail page. (If you don't see Trash along the left side of your Gmail page, go to the Labels tab in Settings, then click the show link next to the Trash label.)
3)Locate the message you'd like to move to your inbox, and check the box next to the sender's name.
4)Click Move to Inbox.