problem with growing plants in minecraft [closed]

While it's individual to given plant, in most cases applying bonemeal (right-click the plant while holding bonemeal in hand) makes them progress towards grown phase, and there may be other requirements. In particular, light, the right 'soil' type, enough space for growing, being submerged in case of aquatic plants, neighboring water etc.

The effect varies with plants - e.g. in case of wheat, carrots, beetroot and potatoes, it causes them to progress one or more stages of growth towards maturity. Kelp, the two vine types from the Nether and Bamboo grow taller. For tree saplings, there's a random chance it will progress through one of two stages of growth, the first is visually indistinguishable from 'newly planted', the second is fully grown. Similar rules apply to crimson and warped fungi. Bonemealing grass and nylium blocks sprouts 'natural vegetation' (tall grass, flowers) in the bonemealed block and several neighboring blocks. Bonemealing tall flowers makes them drop another flower of the same type as an item. Pumpkin and melon stems can be bonemealed to maturity but after that the chance of sprouting a melon or pumpkin is random.

There's a number of plants that don't react to bonemeal - sugarcane, cactus, vines (regular swamp type), Chorus - in their case you must defer to natural growth (which applies to all plants) - random ticks. Random ticks occur within 128 blocks horizontally from the player, so plants will not grow without a player in the general vicinity; without getting into deep technical details, occasionally blocks (including plants) receive a random event that acts similarly to applying bonemeal - attempt to grow (with a certain chance), progress a stage of growth etc. Usually the conditions for successful growth are at least, if not more strict than in case of bonemealing.

Bonemeal can be obtained by crafting it from skeleton bones, uncrafting bone blocks (plentiful in soulsand valley), composting various plants, foods and plant matter in a composter, and as a random drop from fish.

Addressing the problem of 'plants disappearing' - there is a number of ways by which plants can be broken or destroyed. Rabbits steal carrots. Foxes pick up sweet berries. Most crops, grown on farmland, will pop off if the farmland is trampled into dirt, or light level drops sufficiently (night sky is okay, cave darkness requires lighting). Sheep will eat tall grass, endermen steal pumpkins and melons, and all kinds of mobs will trample farmland. Watch out for these problems.