DVD drive not found

This is the common problem in windows 7. Sometimes you find that your DVD drive is not found even if your BIOS showing the DVD drive. So the question is that how will you remove this problem? This is a Windows 7 installation problem. Solution is here- 

Open RUN and type the REGDIT in it and press Enter. Now you have to browse for the key HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\{4D36E965-E325-11CE-BFC1-08002BE10318}, then you have to delete both the upper and lower filters in the right hand panel. Now you DVD drive should visible if not then try to change the drive letter. To change the drive letter you have to click on the Start button and type Disk Management in the search box and choose the Create and format hard disk partitions link. If you see your optical drive here then Right click on it and select the Change Drive Letter and Paths, click on the change and choose a new letter. Now you can find the drive in your explorer and you can also switch back to old letter. If it is still not visible then restart your computer. I hope it will show you after it.