QSI SBW242B Optical Drive

My first post, so please make allowances! I've read the FAQ's and searched the forums before posting.

My laptop has a QSI SBW242B CDRW/DVD drive. I have used it to play a few DVD movies and load some software from CD but that is all.

Yesterday I disassembled the laptop in order to install another stick of memory - unfortunately in this laptop the memory slots are directly beneath the keyboard. After re-assembly I find that the optical drive will not read DVD's, will only read some CD's, and will not burn CD's.

OK obviously I have somehow goosed the drive. I don't know how, as all I did was pull it out of the case and then later push it back in. I've tried re-seating it a few times but without improvement.

I intend to buy a replacement drive. My question is (not knowing a thing about laptop drives): just how interchangeable are laptop optical drives? Are they pretty much made to an industry standard shape, size and connector or do I need to get one specifically for my laptop? The laptop is a Medion Sim2000 which is made by MSI.

Thanks in advance for any help.