Sorry to hear about this. Is this happening with any specific media type or is it with all of them? Also, have you tried switching the Renderer to Mercury Playback Engine Software Only & checked if it's working properly?
Before we learn how to sharpen an image with Unsharp Mask, it's important to note that sharpening an image is not the same thing as adjusting the focus. Photoshop can not go back in time and change the focus point of your lens or remind you to bring a tripod. A blurry image will always be blurry no matter how much sharpening you apply.
Sharpening is about making the in-focus areas of your image look sharper, and that's what we'll be learning how to do in this lesson.
To follow along, you can use any image. I'll use this image that I downloaded from Adobe Stock.
Since this is a macro shot, much of the image is blurred out due to the shallow depth of field. But in the areas that are in focus, there's lots of fine detail I can sharpen, including the area around the frog's eye, the skin texture, and along the edge of the leaf: for further details