Unless this is a new computer where your original iTunes Library does not exist, subscribing to iTunes Match, does not remove songs from your computer. It only copies them or matches them to existing songs in the iTunes Catalog.
If this is the same computer you originally subscribed to iTunes Match on, your songs would be in the same place they have always been. Normally that is the iTunes Media folder inside the Music folder in your user profile. Unless you moved your music library to some other location on your hard drive or to an external hard drive.
You can "control+click", right click or two finger click, on a specific song, and then click on Show in Finder to open the Finder to the specific location of the song file.