Actually, we need more details.

Is this an in-ground or above-ground pool? What are the dimensions/shape roughly? How many gallons?

If it is in-ground, is it vinyl, fiberglass, or concrete/tile/plaster/gunite/shotcrete? What is the liner's condition--torn, cracked, patched, whole?

What is the condition of the plumbing? For IGs this can be expensive to repair. For most AGs it's a snap.

So the first question is: Is the pool physically and mechanically sound? If not you need to fix it before you can do anything else.

If it's just water, algae, mold and debris, you can bring the pool back to life.