It helps to have two people on the job, plus a length of netting or a piece of hardboard or similar, for herding. 'One man and his hen' is more difficukt, at least without canine assitance. One person stands by the gate to the run, keeping it shut so the others don't all get the chance to join in the fun, and ready to open it in such a way that the door itself makes a barrier to stop the hen going off sideways when she approaches. This is why its better to have the door opening outwards, not in. With only one person, its hard to get ahead of the hen to open the gate without scaring her off round another circuit. The second person, armed with the herding netting or other implement, gently walks behind the hen, trying to funnel her towards the door and heading her off from behind or at the side when she moves out of line. Easier said than done, but possible if everybody is very quiet and slow-moving to keep her calm.
If only one person is available, another way is to create a sort of funnel to herd her into a narrow corner somewhere, and when she is confined to the
pointed end, just get hold of her in the usual way. If she is a leghorn and inclined to fly up, it will be easier if she can be herded somewhere where she can't do this.
And of course, this problem only occurs with hens that are not tame enough or hungry enough to realise that going back into the run means rewarding with a handful of corn to peck at. Once they get this into their little heads there's no problem except avoiding getting knocked over in the rush. I haven't found sprinkling corn on the ground outside the run is effective - the hen will come and eat the corn, but will keep a very wary eye on you and will move away at the first sign if your moving to capture her. You just have to get her to want to go back in, and then in a familiar, confined space, cornering her is quite easy.
All easier said than done - my Leghorn has recently decided she will give me the runaround and last week she got herself stuck between the mesh of the run and the mesh of the adjacent garden fence, struggling herself into what was an aperture if decreasing width between the two, in a place where I couldn't reach her to help. I had to get a brush, slide it between the two layers of mesh, and sort of 'persuade' her from below to struggle free in the opposite direction. She did emerge unhurt, but very alarmed, so then catching her was far worse, though t east she don't ly up and over into the next door garden, with their two big dogs. Of course they always do thus hen you are in a hurry to go out, don't they? I expect they sense I'm not fully relaxed, or maybe it happens at an unusual time of day in their routine.