You should first allow hidden file to be showed, you can clic organize >folder and search options. in the popup wondow clic on tab "view" then mark "show hidden files, folders and drives" when that's done go to
C: user > username(your comp user name) > appData > Roaming > apple computer > iTunes > iPhone Softwarw Updates. Check in that folder if you have the ipsw you want to install in on your phone. If yes you can copy, NOT CUT the ipsw to another location like to your desktop. If not, then google for it and download it from google.
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