Restore using recovery mode. If you've never synced with iTunes or set up Find My iPhone in iCloud, you'll need to use recovery mode to restore your device. This will erase the device and its passcode. 1  Connect your iOS device to your computer and open iTunes.
So if you have a .deb file: 1  You can install it using sudo dpkg -i /path/to/deb/file followed by sudo apt-get install -f. 2  You can install it using apt-get install package_name. 3  Install gdebi and open your .deb file using it (Right-click -> Open with).
You may be able to download this from a web site or if it's in the Ubuntu repositories you can download with. Replace package with the name of the package. Once you have your de file call dpkg directly from the command line. The following example will install package.deb into your home directory.