Did "he" rip off just one cotyledon (baby leaf) or both? If just one, your plant has ime a 50/50 chance of surviving. I had one rip it's own cotyledon off leaving the shell behind in the soil and it survived long enough to grow some true leaves and overcome the stress. Grew into a nice plant. Another time I did what "the guy" did, and it died. Those were both in my first grow. Now I just mist it and leave it for a while under a humidity dome to soften up the shell and the membrane under it. Usually the plant pops em both off itself. If not then you can take a q-tip, moistened and start trying to very gently push them off, making sure to keep them moist and soft.