Search is showing results from my other store

You've probably duplicated the theme of that other store.

Please do the following:

1. Open the Shopify Admin for your site.
2. Open theme.liquid in the Shopify templating system
3. Remove the InstantSearch+ or Fast Simon snippet that's been copied there.
4. Go to collection.liquid and replace the ISP or Fast Simon collection snippet with the one found under the Collections tab on the Fast Simon dashboard.