While I was in the festival zone Esior's cove in the Water Cave [when you leave start point go right untill you come across a bridge and than go down the lake untill you reach the cave] I came across an egg and collect adopt it but then the game said I abandoned the egg but i didn't i clicked adopt now im confused and really upset I know I have plenty of room in both my Hatchery and stables and I definitely clicked adopted I'm not sure what is going on

I was probably a glitch you need to message Krinadon and tell him about it.
Casmere

Unfortunately, I would have no way to recover a past Sylestia Nest event. Once it's adopted or abandoned, it's permanently removed from the database. The only way it would not have been adopted was if the Leave It option was selected.

My best guess is just that it was accidentally selected when the event popped up.

If you are using Tigress's amazing extension you can press E to accept the egg or R to abandon(i assume). I just tested it and E does indeed accept it. I havent tested abandon xD