I have samsung octoedge speedplus dvd rw in my p.c some time we can open dvd and sometime the computer cannot detect dvd in my computer.

Click start control panel administrive tools,computer management,device manager scroll down cd-dvd rom drives you might see a yellow question mark ? right click you will have options to update driver,roll back driver,or select properties general troubleshoot, select driver click to reinstall drivers click update driver or uninstall then reinstall if this does not fix the problem it might be a registry problem if you cant see your disk drive in windows explorer
Close all open programs:

Click on Start, Run, and type regedit and press Enter:
Click on the plus signs (+) next to the following folders

HKEY_LOCAL_MACHINE

SYSTEM

CurrentControlSet

Control

Class

{4D36E965-E325-11CE-BFC1-08002BE10318}

This folder is the DVD/CD-ROM Drive Class Description in the registry. Look for any of the following names in the right hand column.

Upper Filters

Lower Filters

Upper Filters.bak

Lower Filters.bak

If any of the above keys shown in step 4 are listed, right-click on them and choose Delete

After deleting the keys, close the registry editor
Reboot your computer
Open My Computer and check to see if your CD or DVD drives have returned. You may also want to open Device Manager and verify that the yellow exclamation and error code on the CD or DVD drive is gone. or
you might have to physically unplug the leads for this cd/dvd then plug them back this should activate the found new hardware wizard or
you might have to uninstall then restart your computer then reinstall your DVD/CD then reinstall the driver for this device:
if your computer came with a motherboard disk the drivers could be on it
click start control panel administrive tools computer management device manager scroll down cd dvdrom drives if you see a yellow question or exclamation mark?! or a red x right click you will need to update the driver or
select properties general troubleshoot, select driver click to reinstall drivers click update driver
hope this helps