All the videos from my iphone are vanished

Are you using iCloud Photos and synced your photos and videos to iCloud, and deleted the videos from your phone after that? In that case, they have also been removed from iCloud. All changes you make on your iPhone are reflected in iCloud Photos as well.

You might be able to restore those videos, if they are still inside the "Recently deleted" album in iCloud Photos on your phone or in iCloud.

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