a while back, i disabled spotlight cause the process mds was totally consuming too much ram.
with improved spotlight in snow leopard, i decided to give it a chance, but totally forget how to enable it back!
so here’s for the reference:
To turn Spotlight Indexing OFF in MAC OS X 10.6 Snow Leopard
sudo mdutil -a -i off
To turn Spotlight Indexing ON in MAC OS X 10.6 Snow Leopard
sudo mdutil -a -i on
Just type the respective command in terminal.
If this don’t help you may follow the instruction on the link in reference.
Reference: Spotlight won’t work?