Last thing you can try is a registry fix. Sometimes the registry keys relating to the DVD drive get corrupted and this can stop the drive from working.
Open regedit and find the key:
HKEY_LOCAL_MACHINE/System/Currentcontrolset/Control/Class/
Right click on the key:
{4d36e965-e325-11ce-bfc1-08002be10318}
Export it to a safe place in case this doesn't work.
Now go to the right pane and delete the keys named UpperFilters and Lowerfilters.
Close regedit and restart the computer. Windows should now detect and reinstall the DVD drive.
Let me know if this works.