Well if you made a backup maybe you can get them back but check these options first.
You don't say the ios version your using nor the version of clips, that makes it harder for us to possibly help you.
Anyway is your version of clips still working cause the latest ios version requires a update to the latest clips so maybe after updating clips you might find your vids.
You can also connect your iPhone to iTunes on a computer if possible and check the File Sharing section to see if your clips can be found there.
Apple Clips https://apps.apple.com/us/app/clips/id1212699939