Place the damaged vertical blind slat on a table so you have adequate space to perform the repair.
Examine the damaged hole and use scissors to cut off any remaining plastic bent in an upward position, such as as the sides of the hole. If the upper portion of the hole is still in place, cut it off as well.
Open the package of vertical blind clips and insert one over the top of the slat until the hole in the clip is over the hole in the slat.
Place a pair of needle-nose pliers on the left side of the clip and squeeze them to crimp the clip closed. Repeat the process on the opposite side of the clip. Some clips stay in place by themselves without crimping with pliers.
Place a step stool under the head rail of the blinds and locate the hook without a slat on it. Raise the repaired slat up into position and hang the hole over the hook. In some vertical blind systems you simply push the slat up into the hook instead of hanging it.