If someone sniffs paint fumes once deliberately to get high, will their brain ever fully recover and will their brain cells regrow if they never do it again?

First off I will say this is a very stupid thing to do but what happens to the cells of the brain is that they may be temporarily deprived of oxygen which has been replaced on the corpsucle by the chemical inhaled. e. g. ever

Is there any evidence that proves that Marijuana destroys brain cells?

Not really, but it doesn't matter if there is a purely neurotoxic effect, as abuse of marijuana can lead to a decrease in cognitive function with associated morphological changes in the brain, as well as an increase risk of psychosis.