When you run the command
ls -la /dev/dvd
in a terminal, what is the output?
I'm having a strange problem, I was able to burn a DVD using K3b but I can't mount it to verify if it burned properly.
I've made a dvd directory in /mnt and tried variation of sudo mount /dev/dvd /mnt/dvd like sudo mount -t etc. or sudo mount -a etc. but nothing seems to work.
When you run the command
ls -la /dev/dvd
in a terminal, what is the output?
lrwxrwxrwx 1 root root 10 Jul 27 2004 /dev/dvd -> /dev/cdrom
hmm, looks like there's something corrupted with the DVD - since another one worked fine :/

Seagate ST500DM009 BarraCuda 500 GB 3.5" SATA III Desktop Hard Drive
$14.99
Western Digital HUS726T4TAL5204 4TB 7.2K SAS 12Gb/s 3.5" 512e HDD NetApp X375A
$49.00
5x HGST Ultrastar 4TB SAS 12Gb/s 7200RPM 3.5" HDD HUS726040AL5214 4Kn
$199.00
HGST 10TB Ultrastar SATA 6Gb 256MB 3.5" Enterprise HDD 0f27452 HUH73101ALE600
$170.00
Toshiba 14TB MG07 MG07ACA14TEY 7.2K RPM SATA 6Gb/s 512e 3.5" Enterprise HDD
$299.00
Seagate ST1000VM002 1TB 5900RPM 3.5" SATA 6GB/s HDD Video Hard Drive PC DVR
$24.99
Western Digital 2TB 7200RPM 3.5" (WD2002FYPS) SATA tested 98%-99% health
$29.99
Seagate Exos ST10000NM002C 10TB CMR 7200RPM SATA6Gb/s 3.5" Enterprise Hard Drive
$279.99
Dell EMC WD-HITACHI H5H72101CLAR10T0 10TB 7.2K SAS 12Gb/s SED 3.5in A POH 0-50k
$189.99
Dell Constellation ES.3 3TB Enterprise-class Hard Drive (Wiped & Tested)
$39.00