CD-Key lost, help!

[Cachaceiro 1]

Hello, first of all, sorry if Im posting this on the wrong place, if so, please redirect me, and second, sorry about eventual errors on my spelling, I dont speak english so well. Anyway, lets go to my problem: I bought Arma:II and Arma:2 Operation Arrowhead from Steam, with the intent of playing the mod DayZ. Everything went well, until some hackers started to show up and kill players, and I died because of then more than once, losing hours of gameplay. Then I decided to also download a hack, with the intent of defending myself from these assholes, but it ended up being a virus that stole my CD-Key, changing it for one probably banned or invalid, because every time I try to enter a server, it gives me the "Bad serial" message. I know nobody will believe that I didnt have bad intentions, I dont even wanna try to get the CD-Key back, what I want to do is buy the game again on steam, but the problem is that it thinks I already have it, and dont let me buy it for myself. Please help me find the solution to this.

Thanks.

[Harzach 2518]

...Then I decided to also download a hack...

...Please help me find the solution to this.

Buy yourself a new copy and consider it a lesson learned.

[TheFordMan 1]

If you buy a new game, I would recommend steam because you will always have it.

[tonygrunt 10]

First of all can you retrieve your old cd key back with a verify integrity of game cache?

If not and your registry key is still the bad one, you won't be able to enter a new one even if you buy it.

[W0lle 1052]

Contact Steam support, or use another email to create a new Steam account.

As Harzach said, lesson learned. Next time stop downloading hacks just because some other people do so and ruin your game.