Nvm already fixed
If anyone wants the same operation to be done then:
1. Remember your old cd key
2. Backup your profile folder (located in
players/profiles)
3. Install game using
old cd key
4. Drop your saved profile folder to
players/profiles
5. Run game, go
Options -> Multiplayer Options -> CD Key and change it to your new cd key
5.1
Dont quit game otherwise your stats will be reset
6. Join a server, play some time to make your stats changed (few kills, deaths etc)
6.1 Now you can quit game.
If you are just changing cd key (ie cracked -> original) without reinstalling game itself then skip 1 - 4 steps