Due to our recent engine update, not all anti-virus software has had enough time to identify Toontown Rewritten as a false positive, which makes it delete a key file needed to run the game! For now, you can add TTREngine.exe to your anti-virus safe list to fix the issue. Check out your anti-virus' website for information about how to do this.
If you have any trouble or run into further issues, let us know! Just send an email to support@toontownrewritten.com for help.