AG pool liner keeps falling off

I moved to a house with an oval above ground pool that was closed for 2 years. The water was black and tried to clean it for 3 weeks but not luck so I emptied it and cleaned it but when I started putting the water back the liner came off of the sides so I emptied again and put sand under the liner and put a inch of water during the hot time but the liner is coming off again.
I don't know what to do . Should I get a new liner ? Or is it another way to fix it ?

Vinyl liners tend to lose their elasticity over time. If you keep the pool full, everything's fine. But if you drain it, the liner may draw up, and then not be able to be restretched.

If your liner is more than 3 - 4 years old, you may want to consider replacement. You can try draining again, during hot SUNNY weather, and see if you can stretch a hot liner back into place.

. . . membership updated.