There is a confirmation message before releasing every pokemon, is your oddish level 7 that important?
There have been cases in which IF you have the ID of the pokemon screenshotted (shown when you free a pokemon), a pokemon can be restored, but they usually were level 100. Oddish is a really common pokemon, and the intervention of an admin would be really inappropriate to restore an oddish :)
So in the very first place, do you have the ID of the released pokemon? Because without that nothing can be done anyway to restore the pokemon.