My network, volume and mail applets disappeared from my top panel.(Original from install). Where and why did they disappear? any insight?

No idea why... doesn't happen to me....
I assume your running Gnome

right click the top panel and "add to panel"
find the missing applets and place them back....

then make sure you right click on the applets on your panel and make sure they are locked to the panel

goodluck

I can replace them using the manner you suggest, but that's not the problem... The real question is where are the originals going? The functionality is similar, but not the same, when adding to panel.

For example: The old mail applet showed when I had mail. The applet I had to add back to the panel doesn't.
Same with the Networking applet. Original gave the option to enable/disable networking, wireless, etc... the new goes straight to connection properties.

Also, the old applets WERE locked to panel, shouldn't make a difference there.

I may be nitpicking, but I just want my panels to stay the way I set them up!

almost forgot... I am running gnome.