Hi just installed some contrails recently but they seem to not be working because I just get black smoke that is squared coming out of my engine. 

 

Could someone send me the default fsx contrails please would help alot  PM if you have time to thanks so much. 

In this thread, the problem you're describing was fixed by using a freeware tool named Gauge Recovery. Maybe it can help you, too. There is no legal way to send you the default contrails, due to the copyright protection, but if the above program does not work, you might be able to get the default files back by using the repair function of the FSX setup.

Ok I will try will it delete any of my custom things from REX 

Brilliant repair! Done in seconds!