ineffective
Not working well or not getting the job done.
Ineffective means not producing the result you want or need. When something is ineffective, it fails to work properly or accomplish its purpose, no matter how hard you try.
An ineffective studying method might involve reading your notes over and over without really thinking about them. You spend hours at your desk, but when test day comes, you can't remember much. An ineffective medicine doesn't cure the illness it's supposed to treat. An ineffective leader might give confusing instructions that leave everyone unsure what to do.
Ineffective doesn't mean something is harmful or makes things worse. It simply means it doesn't work. A broken flashlight is ineffective because it fails to provide light, but it doesn't make the darkness worse.
Sometimes people confuse ineffective with inefficient. Something inefficient wastes time or resources but eventually gets the job done, like taking a long, winding route to school. Something ineffective doesn't achieve its goal at all, like following directions that lead you to the wrong building entirely.