Hey there! First off, take a deep breath we have all been there. "Helicopter parenting" your plants is a total rite of passage for a new grower, so don't beat yourself up too much!
Looking at your photos, it looks like you had a little mishap and split or snapped the main stem while readjusting your LST (Low Stress Training). The good news is that cannabis is an incredibly resilient plant, often called a weed for a reason, and it can bounce back from this beautifully if we act fast.
Since this is an autoflower, time is a bit of a factor because they have a built-in internal clock and less time to veg and recover than photoperiods, but your plant still looks young, healthy, and full of life.
Here is what you need to do right now to save her. You want to treat this like a broken bone. Bring the broken pieces back together as perfectly and snugly as possible so the internal vascular system can reconnect. It looks like you've already tried taping or wrapping it with what looks like a pipe cleaner or string, which is a great instinct, but we need to make sure it is totally stable and sealed. Get some electrical tape or specialized grafting tape and wrap the break firmly to hold it in place and keep moisture in while keeping bacteria out. If the stem is sagging or can't support its own weight, use a small wooden skewer or a chopstick as a splint alongside the stem, taping it firmly to give it structural support.
Once she is patched up, leave her completely alone for at least a week to 10 days so she can form a protective knuckle over the wound. Avoid any more LST or stress on that specific area until it is fully healed. You might notice a little bit of wilting above the break over the next couple of days, which is totally normal, but as long as the tape holds it secure, she should mend herself just fine. Keep your chin up, you've got this!
Happy Growing Growmie🌱