Your account is not disabled. Your workspace is active on the Free plan with a $0.00 credit balance, so your deployments have been stopped because your credits are exhausted. The Free plan provides $1 of credit per month, which will let you run services in serverless mode when it replenishes. To run services continuously, you can upgrade to the Hobby plan ($5/month, includes $5 of usage).

"My account was reactivated, but I don't see my original project (the one with the production MySQL database, a service that's been active for months). I only see two empty projects with random names. Was the original project deleted when the account was disabled, or does it still exist somewhere?"

Your projects were not deleted. You have two projects ("fantastic-friendship" and "laudable-tenderness"), each containing a MySQL service with a persistent volume holding ~150 MB of data. Those names are auto-generated by Railway, which is likely why they look unfamiliar. Your deployments were stopped because your credit balance reached $0, but the services and all their data are still intact and will come back online once you upgrade or your monthly credit replenishes.