If all else fails you could connect with itunes on your PC/ Mac and do a backup and then do a iphone restore. This will restore your safari app back on your device then reinstall from your backup. There are other and some say better and more useful browsers on the app store.
Thank you to the community for your replies.
I hate when I move an application and can't find it or when an application disappears. I'm sure with your help we can get this fixed.
Is Safari the only application that is missing? Is the device Set on Wifi? To check: Press the home button>Settings>Wifi. Please turn of Wifi and retest.
If its still missing let's reset the device. Press and hold the top and home button together for approximately 15 seconds until the apple logo appears then release. When the device resets the Safari application should return.
Please let me know if this helps, if not I'll gladly further troubleshoot with you.