At some point my sig and ava were converted from xyz format to jpeg and quality was lost. Is it possible to have the images 'sharpened' up again?

I'm very noob at photo editing. I have used Paint.NET before for very basic modifications.

If you lose the quality, sharpening will only highlight the pixels and make it look terrible.

Maybe sharpening is the wrong word, I essentially want to enhance my images.

Try some magic find, it's wunderbar

a little hint:

Your sig has already ruined the stock of that picture anyways