How to respawn an object?

Question

2D

For example, there is a platform if you step on it, it falls and is removed. How can I make it appear again in the same place after a while?

Answer 1

Do not delete the object, but turn off its display (and the collider so as not to get up again) and remembering the starting position, turn it on again by the timer, placing it at the starting coordinates.
If you want a direct code example, then look ahead and read the official tutorials from Unity on how to do basic things.