how to deal with failure?

so I failed this really important exam and now I have to retake my year. it was really surprising because I worked really hard and didn't expect to fail :( now I'm worried about retaking it next year and failing again and I just feel ashamed since most my friends succeeded while I didn't.
it's my first "big" failure and I don't really know what to do. I hope I can receive the advice of people who went through this before!