HEIC files corrupted?

Are the .heic files really corrupted or does your Windows setup just not support them? Can you upload such a .heic back to the iPhone and check if it is displayed there? Or download .heic support add-on for Windows (sorry, I have not yet tried that in my rarely used Windows 10 setup)? Can you post such .heic file in some cloud service (Dropbox, iCloud etc) so we could check if it really is corrupted?

Ace8178 wrote: ... any way to get photos back that were down loaded?

If they're gone, then they're probably gone, I'm afraid. The usual steps include these:

If you're missing photos or videos in the Photos app - Apple Support

Basically the above says to look in Recently Deleted and in Hidden. Check your Library thoroughly-- the pictures may not be where you expect. You can use the search field with the date or location.

If you use iCloud Photos, then you can look in iCloud.com.

If you don't use iCloud Photos, but you have Settings>Apple ID>iCloud Backup turned on, then you may be able to recover data from the last 30 days or so at iCloud.com. You should look here:

View and manage iCloud device backups - Apple Support

If you don't keep your own backups, there really isn't any place else to look.

If you can see the pictures on your iPhone, then you may be looking are "preview" copies. If they are special to you, you can make screenshots of them and export those. They'll be lower resolution, but at least you'd have them...

Did you upload these to a Mac? HEIC is a newer, more efficient format, and some software isn't up to speed, yet, but Mac software should be OK.

If you want jpgs to be more compatible, then you can set the phone's Setting>Photos>Transfer to "Automatic." And you can use Settings>Camera>Formats set to "Most Compatible." Try saving them from your phone with these settings and see if that's better.