I think it's pretty annoying that PracticePvP has so much hackers. At this moment I have 1450 elo and I really hate when I get killed by an hacker and lose like 20 elo which takes me 4 wins to get. So my question is can i get this elo back if I have proof that an hacker took my elo?
No, Elo refounds are not a thing unfortunately. If you're feeling like you want to be helpfull towards the server and kinda vindictive towards those cheaters be sure to record your fights so they get banned. If you want an extra tip, try to stay away from the melee based ladders such as Nodebuff so you can keep them at long range.
Just as Andrew said, Unfortunately that isn't a thing. However if you record your fight against a hacker and report him, it would help you from running into the same hacker again and in turn, losing more of your elo. Bygones will remain bygones, but you should still report them to an admin in-game, or on forums if no Admin is online.
Its okay dude, since I am a high elo'd player it takes me quite some time to find matches and when I do get those matches I have to make sure not to lose because I normally lose like 30 elo. Just keep at it and you'll make it back in no time!