My website used to have a couple hundreds of inbound links. Just today. Those inbound links were gone. My website is still index. Is this normal?

Very normal. These numbers tend to fluctuate depending on many factors. I wouldn't be too concerned in the short run. Check some of the other SEs to make sure that those are still normal, and just keep working on building good inbound links. You should be fine.

In Google, and MSN, the inbound links are normal. Hopefully, Yahoo will finally rank me. Yahoo is a little slow to find inbound links lately.