Use the Roblox Help Center: https://en.help.roblox.com/
Sign in to your Roblox account
Go to the support/contact form in the Help Center
Submit a support request with your issue details
For account recovery, use the account recovery options in the Help Center
For billing issues, use the billing support section in the Help Center
For safety or moderation concerns, use the report or support options in the Help Center
Check the Roblox status page for service issues: https://status.roblox.com/