Please help my avocado :(

[MissA]

So... a few days ago, I noticed there were crawling little white insects in the soil, so I decided to re-pot my avocado, seeing as I wanted to avoid root damage. I was being very careful with the plant's roots, making sure nothing gets squished down in the pot. I then placed it in its usual spot (where it had been thriving, btw). One day later, the leaves started looking droopy. I watered it, but nothing changed. Just looking at the plant now, 3 days later, it's worse than ever.

The soil is moist, so it definitely doesn't need more water. I'm afraid the avocado will die, and I'm really attached to it lol.
Please help!! What do I do to help it?

 

[Tetters]

Welcome to the forum @MissA

If the white mites, or root aphids have caused the problem to your avocado, you needed to wash all of the old compost away totally to ensure none were left. The roots on the plant should be white - like cooked spaghetti. If they are brown or black your plant is on the way out for sure.
Assuming the roots are healthy still, the new potting compost should be very light and sandy, as the avocado cannot bear to have its feet in water, and overwatering can be an enemy in this case.
If you decide to use an insecticide on the new compost choose one that contains pyrethrins. Good luck