address book

I have an i-mac with 10.4.11 tiger on it - turned it on, and nothing on desktop
(I usually leave files there that I am working on) address book empty except the apple
head office, don't know how - was trying to find copy of upgrade to leopard osx on internet
last use.
question: can I get it back - the address book preferences are gone, and there is nothing
in the library file. Where do I check next?

Welcome to Mac-Forums

Have you been running any sort of backup on this iMac? You cannot find the Leopard upgrade online, you will have to purchase the retail copy from eBay or someplace to do the upgrade..

Is it just the addressbook content that is missing or other stuff as well? Are you certain you've logged into the right user if you have multiple user accounts on that machine?

I found the rest of my files in weird places on my hard drive, I had left pictures in an open photo
booth program and lost them, I only have 1 user on this computer. I completely shut down when I left that day (friday)
I did not know at first you could not buy the upgrade from apple and I know I clicked on a website"ask"
that said it was free and it took me to mackeeper to buy, could I have picked up something that would
do this, I did put my system and everything my virus scanner and said it was all fine.
I found a file called addressbook.data but I cannot open the file, no program will open it either.
This has about 10 years worth of addresses etc. - never had a problem before.

Do a search for mackeeper on this forum. If it is not the cause of this problem it will probably be the cause of your next one.