Cannot see CD Drive (Windows 7)

A few months ago I had this problem - I could not see the CD/DVD drive on 'Computer' and could not play DVDS/CDs. I found a solution - that did not involve registry tweaking - and it worked (I think I had to tick a box in a drop down menu) - but I caanot remember what I did.

Today the problem has returned.

I have downloaded the TSG Information program and here is the info. Any help would be appreciated.

Tech Support Guy System Info Utility version 1.0.0.2
OS Version: Microsoft Windows 7 Home Premium, Service Pack 1, 64 bit
Processor: Intel(R) Core(TM) i3-2350M CPU @ 2.30GHz, Intel64 Family 6 Model 42 Stepping 7
Processor Count: 4
RAM: 4039 Mb
Graphics Card: Intel(R) HD Graphics Family, 1795 Mb
Hard Drives: C: Total - 431937 MB, Free - 346359 MB; D: Total - 29690 MB, Free - 27446 MB;
Motherboard: LENOVO, Base Board Product Name
Antivirus: Microsoft Security Essentials, Updated and Enabled

Many thanks

John