Stuck at work

If you mess up on a client engagement and can't finish a task properly? What happens ? What are the repercussions? I'm a fresher and I don't know what to do anymore ? Is this normal ? It's only been 7 months here , I'm a campus hire and I feel out of my depth? Seniors don't help that much as they're too busy? My anxiety is really high and I don't know really know what to do anymore. Any tips advice would be helpful?