iMovie 15 import error

Basically, when i open iMovie 15, find a clip from my library that I want to import, and I click the import button, nothing happens.

Recently I was cleaning up my Macbook Pro's diskspace with an app I downloaded from the internet called OmniDiskSweeper. I chose to delete what seemed to be copies of old iMovie projects. I have a suspicion, that I might have deleted some important iMovie software on accident during this process, and am accusing this of being related to the iMovie importing error.

Should I delete iMovie and reinstall it, or is there a way to fix it otherwise?

Thanks!