Often it just needs adjusted. If you have all of the parts, your kickstand can likely be reassembled and adjusted.
If you have lost some of the parts, please determine which style you have here and use the provided links: Kick Stand Replacement

A telltale sign of this issue is that you can hear a rattle from inside the adjustable portion of the stand. That would be the nut that helps to tighten the bolt. You can see in the pictures below how it's profile matches that of the kick stand. Howver it must be in the correct position.This means that the small nut that is meant to seat that bolt is now loose in the end of the stand. It is meant to attach to the bolt that tightens/locks the location of the sliding adjustable portion of your kickstand. This little nut has come off inside the kickstand and is now loose and rattling around.

You may ask yourself, can I get a replacement or can it be repaired?

Do not worry, this is easy to resolve at home and does not require waiting for a replacement part.

If there is a rattle in the adjustable portion and you can just spin the screw endlessly:

  1. Remove the bolt and slide the adjustable portion off
  2. Locate the shaped nut with threaded hole shown below.
  3. Orient it properly and carefully slide it in to match up with the hole
  4. Reseat the screw in its insert
  5. Slide the adjustable portion back on 
  6. The seated nut will now work as an anchor for the adjustable portion again when you tighten the bolt.