That was a bad idea. ROTMG stores some settings in a local storage file (an .SOL file if you want to look for it - the .SOL files for all Flash apps are normally all in one place), including your keyboard preferences, whether you have been to the Tutorial, and your most recent login.
So if you delete that file you will have to recreate the settings. Normally that’s it – you log in, and go through all your settings and you are set to go once more. If that doesn’t work it could be something else is stopping it create that file, such as the OS’s security settings or an app which cleans up temporary files and cookies (as the .SOL files are effectively Flash cookies).