If you see your post failed or didn't go out, the first thing you should do is go to your Platform Settings, then next to the social outlet that failed, click RECONNECT, after you reconnect try the post again.
If that does not work here are a few options
1. Go to your Content Calendar, find the post that failed, click on the post, then click Report a problem with this post at the bottom right hand corner, and follow the prompts.
2. Click on the blue circle on the bottom right hand corner of your platform and write out your problem.