Open your blurred photo. I am using this image.

Press Ctrl + J to duplicate your background layer

Go to Filter » Other » High Pass. You may want to set this higher depending on how blurry your image is, as my image isn't too bad I am going to use 5px.

Set the layers blending mode to Hard Light and lower the opacity to 30%.

This is the unblurred version.

This shows the difference between the original and sharpened.