Q: i0s9 upgraded on its own, my phone is stuck at the 'slide to upgrade' screen, i slide type in my passcode, goes to an apple screen loading, then glitches back to slide to upgrade, wont connect to itunes, restrted turned off.. nothing works!

Follow these instructions provided by Apple for this issue:

If the Slide to Upgrade screen won't go away after you update to iOS 9 - Apple Support

Best of luck,

GB

iTunes should recognize the device and ask you if you want to set it up as a New device.....

If it is not working, try to put your device into Recovery Mode and go from there:

IOS RECOVERY MODE RESTORE

Best of luck,

GB

LIke you and many others as well as me we all had the same problem.  Unfortunately resetting the phone is the new only to make it work.  I got it to work by upgrading it to 8.1.4 and then upgrading to IOS 9.  Of course that deleted everything from my phone.  But i couldnt be without a phone until the next update that supposedly will fix this glitch.  There are many links on google that give you step by step.  If possible try to back up everything you may have before its too late.