To avoid having your data deleted if you want to plug your iPhone or other iOS device into a computer that you normally don’t use, you will want to make sure that the auto-syncing feature is turned off. To do this, make sure you don’t plug your iPhone into the computer or iTunes before turning off the auto-sync feature.
The first thing you want to do is to open iTunes and go to either Menu, Preferences and then Devices if you are on a MAC, or go to Edit, Settings and Devices if you are on a Windows computer. Look for a checkbox that is labeled, “Prevent iPods, iPhones, and iPads from syncing automatically”, check that and click OK at the bottom of the window. After you have completed those steps it will be safe for you to plug your iPod or other iOS device into the computer.