How to Rebuild a Search Index in Windows Vista
Once in a very blue moon, Vista’s search index just stops working. There could be a number of reasons, but if it happens to you, it's reassuring to know that Windows Vista makes it easy to rebuild a search index.
Bear in mind that there are lots of reasons why a search index might not find the file you're looking for. So don't jump too quickly into rebuilding your index. However, if search just stops working altogether, or if its oversights are so extended and gross that you know something has to be wrong under the hood, then go ahead and start building:
Wait until you don’t need your computer for a long, long time.
Choose Start→Control Panel. Click the System and Maintenance link. Then click the Indexing Options link.
Vista shows you the Indexing Options dialog box.
Click the Advanced button.
After you click through a User Account Control dialog box, Vista brings up the Index Settings tab on the Advanced Options dialog box.
Click the Rebuild button.
Go out to a very long lunch.
By the time you get back, your system might be re-indexed.