Upscale Headshot to 500×500

I only have my new professional headshot as a tiny thumbnail, and whenever I try to zoom it, the photo blurs badly. I need that same image turned into a crisp, clear 500 × 500-pixel file for my LinkedIn profile.

Please take the thumbnail, enlarge it to the requested custom size, restore lost detail and sharpness as much as possible, and send back a high-quality JPG (PNG as a second version would be great, too). The final file has to look clean on LinkedIn without pixelation or obvious artifacts when viewed at full size.