There are several methods in Photoshop to help but nothing will bring a soft image back to what you hoped for.
A good tool is
Recover Detail and Sharpen Your Blurred Photos and worth buying if you have a number of shots to correct. It has a free trial to see if you like what it does. That being said any of these shots that have heavy post processing done to them will not hold well to big enlargements. I would recommend converting every image to a TIFF before you do any editing to try and preserve as much detail through the edits as possible.
Tough way to say hello on the forums.