I took pictures and videos at a concert but my mom erased them. Is there any way to recover them?

If you backed them up to iTunes or iCloud, you could restore your iPhone from the backup.

Otherwise, they are gone.

Only if you backup them up then you can restore your phone from your backup.

If you imported them to your computer then you can use itunes to sync them back.

If both of the above wasn't done, then those data are gone.