if you have a box spanner, or socket set, that will go over the rod you can place the circlip onto the top of the rod with the opening at the bottom (a dop of grease will hold it in place) then place the box spanner against the circlip, add pressure and as the scoket goes over the rod it will push the circlip along it - famous last words that doing it this way the thing can't spring anywhere!
I have loads of circlip pliers, but unless I wanted to avoid marking/scoring the rod I would use the above process.
I do agree with Chas, the bigger issue is why did it come off - when they come off 'of their own accord' once, they tend to do it over and over again!