Help me please

Make sure you are using a 'hydroponic' fertilizer with coco coir. You provide everything the plant needs.. so, it needs to be a 'hydroponic' fertilizer. if it is any system of ferts that require a bunch of supplements to keep the plant healthy, investigate better fertilizers in future.

Stick with it... you either hit the learning curve now or later. if it's well-prepared coco, re-hydrate and should be off and running. like others said, you do feed everytime wit coco, but if you have a small plant in big pot (previously growing into this picture given), you can easily build up nutrients and cause toxicities for same reasons you would in soil. I started with some cheap coco and ended up with a major k-toxicity. You don't look to have that problem, so that's an excellent sign for the near future. Those will bounce right back with hydrated substrate and fertilizing near the roots, if pot is too big.

Looks like the growing medium is coco-coir? This will complicate things for a first time grower a bit.. If so, she likely under-watered, and underfed. With Coco, you want the medium to remain moist, which will present other challenges later, compared to a traditional soil. (where you would allow the growing medium to 95% dry out between waterings, and there's also some nutrients in the soil). Coco doesn't contain any food, so you will need to feed your plant with nutrients. With a vegetative nutrient mixed into a 1 gallon jug of water, PH'd to 6, you could then water your plant with that every other day, maintaining a level of saturation throughout your coco. When you water in coco, it's best to water with a dosage that allows about 15% of the liquid to run out the bottom of the pot, ensuring that your plants have an ideal diet flowing through their roots.