Give the SDK a try. If it doesn't fix the problem, you're at worst out some time (the download is free). You could also try using the official XAP deployment tool (included with the SDK) and seeing if it works any better.
If the SDK does it for you and re-installing this app didn't, please write a clear bug report (meaning full error messages, etc. "....now i cant ...it says class is not registered ...any help ... i searched its about dll..." is not even close to adequate) so that author and improve the app.
Actually, you really ought to do that anyway. Otherwise, you're not going to get anything except fairly generic troubleshooting solutions like "have you tried the official version?"