Files and Settings on my Mac just dissappeared

I am currently using the Mac OS X 10.4.11. I've been using the computer without any problems for the past 2-3 years. Just yesterday, when I turned my computer on, many of my files which were once on my desktop has disappeared. The odd thing is, when I look at the amount of HD space available, the correct amount of space is still available. If i use the finder, I am unable to find any of the files which have 'disappeared'. All my bookmarks have also disappeared. In addition, I had previously set specific preferences for my trackpad (for example, i could use two fingers to double click) but those preferences seemed to have been reverted back to the original settings and I had to manually change the settings myself. Anyone have any idea what's going on? Is there anyway I can recover the files which had disappeared? I also checked to make sure that I wasn't logged in as another user. Thanks for your help and support.

So all I have to do is change the name back to exactly what it was prior to changing it? Also, If i don't remember the exact name, is there any other way to recover my settings?