How do I undelete some files

[Mark Swanson]

Just when I think I start to know something about computers, I do 
something boneheaded. I "selected all" in a window and tossed that in 
the trash.  In addition to the hundred or so files I intended to trash 
were two folders I really need.  Again, without thinking, though it was 
a couple of days later, I emptied the trash.  The next day, I noticed 
the two folders were gone and wracking my brain, realized what 
happened.  How can I undelete these files?  I am using 10.2.6 and these 
files are on an external drive.  Please help.  mark