"Stuck" CD/DVD drive door

Greetings all!  I am new and this is my first post, so excuse any amateurish mistakes.  I have an Inspiron 1521 laptop running Vista.  The tray that holds the CD's and DVD's is stuck and won't open.  When I press the button that normally opens the door, the green light flashes 3 or 4 times, but the tray does not open.  I don't think that there is a disc is in the drive, but I can't be 100% sure as there are three users of this machine.  It is a home computer.  One possibility of a cause is that about a month ago my wife dropped the unit from a height of about two feet and a corner of the unit landed on the top of her foot.  There was no visible damage to the unit and everything else appears to be working correctly.  I ran the online diagnostics and everything checked out OK.  I have not tried applying any pressure to the door or tried to pry it open using a small screwdriver etc. fearing that I might cause more damage by doing this.

Any help would be greatly appreciated.