We strongly discourage use of so called packet writing software to use a DVD as kind of a gigantic floppy or smallish USB-stick. Those are unreliable, as you see. That's all that can be said about it, since you didn't tell what program you used to write to that DVD, nor anything about your OS (Windows XP, Vista, 7, 8?).
And a more general remark. If you have an original and you make a (backup) copy of it, you have 2 copies. If you delete the original, you've only got one copy and no backup. Then if something goes wrong, it's gone. That's why we strongly encourage members to make a backup, and preferably more than one, of everything they don't want to loose.
Some of our members learn that too late.
It could be the disk isn't 'closed' yet. In that case, it might help to close it now. If not, contact drivesavers.com and ask them if they can recover your pictures and how much it will cost. Most likely, much more expensive than a backup would have been.
So I put a blank DVD+RW disk in my computer and formatted it. I dragged more than 1000 pictures (not all at once though) from my computer and dropped them onto the cd. They all showed up fine. I deleted all the pictures off my computer, then emptied the trash bin. The pictures still showed up on the DVD. Then a day later I took the DVD out of my computer and reinserted it. Suddenly it was asking me to rename the disk (which I unwisely did, with the same name as before) and it showed me a blank disk with no files. What went wrong with the disk? Thank you in advance