Fix Hacked OpenCart Checkout

My OpenCart server was hacked, corrupting the checkout. I need a professional to restore functionality and secure the site.

Issues include:
- Unable to complete purchases
- Missing or incorrect checkout fields
- Credit card and PayPal options replaced by cryptocurrency checkout

Security measures taken:
- Changed OpenCart passwords

I have a recent backup (within the last week) available for restoration.

Ideal Skills and Experience:
- Expertise in OpenCart and server security
- Experience with checkout process issues
- Strong background in website recovery from hacks
- Knowledge of payment gateway integration

Please provide a detailed plan and timeline for fixing these issues.