Mixing and matching frames and forks is pretty advanced stuff. As many have mentioned, it begs the question - why is there no fork? Was there damage to the fork, which might impact the frame?

Assuming the frame is good, it's next to impossible to find an exact match for a replacement fork unless it's of fairly recent vintage. Some of the basic dimensions on the fork, such as axle to crown dimension and fork offset (rake) need to be known, or an experienced shop mechanic or framebuilder needs to analyze the frame geometry, the rider's intended use, take into account the head tube length and diameter, threaded vs threadless, wheel and tire size and type/size of brake, and possibly other considerations to determine a suitable replacement.

I've purchased a couple of frames that did not have an OEM fork. In those occasions I built my own fork to match the frame and how I wanted to ride it. It's really hard to find a framebuilder who will build you a custom fork, and if you do, it'll almost surely cost more than what you paid for a used frame.

I wouldn't buy a frame by itself unless you really knew what you were doing, or had someone that did advise you.