CD/DVD drive disabled/not getting detected

You might some times see that there's a no cd/dvd drive icon in your my computer,this might have caused due to some reasons,so you need to do is
1.Go to my computer,on top you can see system properties or else go to control panel and click on system
2.A dialog box appears containing the following options on the left.

•  Device manager
•  Remote settings
•  System protection
•  Advanced system settings   

3.Click on device manager,then this window will open

you can see the warning mark there ,right click on it and click on scan for hardware changes