How do you stop a command prompt process when using advanced troubleshooting options off of a USB Boot?

I am doing chkdsk C: /R but... That will take forever so I want to stop it and just do chkdsk v: /F instead.

Ctrl+C doesn't work, you can't open Tasklist/manager.

Oh yeah I am doing this because when trying to boot it said the (boot file?) on the drive didn't work/wasn't found, try to repair windows, and when I tried to just repair it said the disk was locked. Ehh don't really worry about this unless you already think you know what's wrong.