Clicking in a product takes user to wrong page

I’ve searched this and other forums but can’t seem to find out how to fix this problem.

When clicking on a product, the user gets taken to the home page where a full size version of the product image appears superimposed on the content of the home page, instead of being taken to the product page with all the product information and the add to cart button.

It was OK about 2 weeks ago, but not when I checked earlier today.

I’d really appreciate some newbie-friendly advice on what I should do.

Thanks

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