"error 75" on my iPhone while trying to restore

Please follow If you see an error when you update or restore your iPhone, iPad, or iPod - Apple Support

If you are using a PC, make sure that you have the most up to date version of iTunes installed. An older version will produce errors with newer iOS versions.

Download iTunesApple SupportOfficial Apple Support › downloads › itunes

If you have more than one Mac, use the newest Mac.