I’m just a newbie here but reading about repositories in the documentation and on the wiki and then some trial and error testing might help you find the problem or at least help others help you.
Did you try installing software with yast2 from your install CD or DVD? Set yast2 filter to repositories and try installing something. If that works the problem may be with repository settings or with internet. If not you had better ask again, Trial and error may not help. If it works then try accessing the URL for the repositories listed in yast2 (open repositories under configuration menu) through your browser. If fails, you could try accessing other (local) mirrors with repositories for your EXACT installation - if you find one you can see, follow instructions in documentation or wiki to list and enable that in yast2 and follow trial and error process again. Dumb solution but it worked for me.