After i do what you said and something appear and written like this :
Error occured (please report this!):\n\nSystem.IO.IOException: The process cannot access the file 'D:\osu!\osu!.exe' because it is being used by another process.
at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)
at System.IO.FileStream.Init(String path, FileMode mode, FileAccess access, Int32 rights, Boolean useRights, FileShare share, Int32 bufferSize, FileOptions options, SECURITY_ATTRIBUTES secAttrs, String msgPath, Boolean bFromProxy, Boolean useLongPath, Boolean checkHost)
at System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share, Int32 bufferSize)
at #=zhPcR_jyQnv4rl79BtKPrrLE=.#=zhQKoeaI=(Object #=zHtVY5E0=, DoWorkEventArgs #=zuMqh1A8=)