Interactive Quiz Website Repair

I need help with an interactive/quiz website that has stopped working. The original developer has gone MIA and I'm unable to get the site to run again.

Key Requirements:
- Diagnose and fix issues preventing the website from running
- Ensure the site is fully operational and can be used for its intended purpose

I possess all the necessary files and have access to the repository. I require a freelancer with:
- Comprehensive understanding of interactive/quiz website development
- Proficient in debugging and troubleshooting
- Familiar with npm and related tech
- Able to communicate clearly and effectively.