Thousands of photos and videos missing from iCloud account

Hi, yesterday I had to change my iPhone due to a broken camera. Instead of using the back up, I decided to set up as a new phone (using the help of the apple store rep) and just backup the important stuff, such as photos and videos.

to start it showed I had about 11,000 photos and videos. This morning, yesterday it got stuck at 4000+ and seemed not to keep synching so I turned off and on the iCloud photo option on my phone.

in the morning, it was still on the same number.

just this time it didn’t seem like there’s anything els to sync. So I went on iCloud.com and saw, that all my photos beside the ones synched to my phone are gone!

I looked everywhere online to find help. And see where the photos have gone to!

i desperately need help!

thank you.