How do you restore old looking fireplace

Here's several ideas for you to ponder over:

https://www.youtube.com/results?search_query=redo+old+fireplace

Inexpensive would be to scrub the fireplace with a powdered cleanser like Ajax or Clorox, water, a few drops of Dawn or a liquid sink soap, and a stiff bristled brush to get into the porous surface. Lay down newspapers or old towels so the liquid doesn’t damage the floor. Have an extra bucket of clean water in which to rinse the brush. You can clean the inside and outside the same way. Best wishes ☺️

https://www.hometalk.com/categories/makeovers/fireplaces-mantels

I have a gas insert and it was necessary to paint it after I bought my 26 yr old home. It requires heat resistent paint. You may also Inexpensively paint it . If you want to spend a little more you may tile it. I had a brick surround around the gas insert that was the same color as the outside brick which looked rustic. I didn't like that look and had it covered over w/marble. Marble look tiles are not expensive. It depends on what kind of look you are going for. Good luck!

Restore what? if you are talking about the firebox and internal chimney to possibly make an old fireplace workable, I would get a certified/licensed chimney sweep.

If are just wanting to restore the exterior appearance, post a picture so we can see what your working with

Embrace the fact that it's an old fireplace. Clean it well and make it a focal point. If you like antique furniture, use a huge mirror over the mantel. If contemporary is you bent, hang a huge piece of artwork.