Q: iOS 10 Beta Restore Help Me

About iOS beta software - https://support.apple.com/HT203282 - "Before you install prerelease software, back up your device in iTunes, then archive the backup. You won’t be able to use an iCloud backup or one you didn’t archive if you go back to the current version of iOS."  Downgrade directions also on this page.

What is the error message?

Put your device in recovery mode and restore it. This should allow you to get back to iOS 9.3.3.

Again more questions than we have answers from you. Which version of iTunes on the computer? Which operating system version on the computer? Which exact model computer?  It REALLY, REALLY, REALLY helps if you quote exact error messages. If you go to a doctor don't you say where exactly you heard something snap when you fell down a hole rather than just say, "I am not feeling well" which may result in you being given an aspirin instead of having your broken leg set?

I am going to guess you cannot restore because your computer is too old to connect to your phone with a newer iOS on it. If this is the case you may be stuck until you can use a newer computer. You really shouldn't be messing with test software if the rest of your equipment isn't up to modern standards.  I use older machines and would never run a beta anything on them.

You have probably identified the problem - your computer cannot run an new enough version of iTunes to restore your iPhone.  If you have a friend with a newer computer, you may want to use it to erase your phone.  Make sure they are running the latest version of iTunes.

Have you been backing up to iCloud?  How long ago did you install the beta software?  Depending upon how long ago you upgraded to the beta software, you may or may not be able to restore from an iCloud backup with the old iOS.  If you erase and restore your iPhone to factory settings using iTunes and try to restore from an iCloud backup, it will need to be a backup from PRIOR to when you did the upgrade.  Restoring from iCloud will only show a limited number of previous backups.  If you use a backup from after the beta was installed, you will have the iOS back on your phone.

Reference "Go back to current version of iOS" at About iOS beta software - Apple Support.

My computer goes into sleep mode and it erases all of the data that has been downloaded for the software update (IOS 9.3.3). I have to re-download it all over again and wait even longer

http://osxdaily.com/2009/09/11/iphone-backup-location/ - your iPhone files are backed up at the following location:

in Mac OS X:

~(your home directory)/Library/Application Support/MobileSync/Backup/