Contact Your Mobile Carrier: Your best bet is to try to regain access to your old phone number. Contact your previous mobile service provider and explain your situation. Sometimes, they can re-issue the same number to you on a new SIM card, especially if it hasn't been re-assigned to another subscriber yet. This is your most viable path.
Contact Telegram Support: You can try contacting Telegram Support However, without access to the phone number or an active session, their ability to verify your identity and grant access is severely limited. Be prepared to provide as much verifiable information about your account as possible (e.g., username, specific contacts, groups you were in, exact date of account creation if you remember, details of your last activities). Be aware that responses can be slow, and success is not guaranteed.
Data Loss: If you cannot regain access, your old Telegram telegram number database account will eventually become inaccessible to you. If it remains inactive for a very long period (e.g., 6 months, depending on your self-destruct settings), it might even self-destruct, deleting all associated data.
New Account: Your only option will be to create a new Telegram account with your current, accessible phone number. You will start fresh with no chat history or contacts from your old account (unless you manually re-add them).
Preventing Future Lockouts (Best Practices):
Always Enable Two-Step Verification (2FA): This is paramount. Set a strong password and, crucially, a recovery email that you have secure and reliable access to.
Have Multiple Active Sessions: Keep your Telegram account logged in on at least two devices (e.g., your primary phone and your desktop/tablet app). This creates an "active session" backup for receiving login codes.
Change Your Number Promptly: If you get a new phone number, use Telegram's built-in "Change Number" feature immediately (Settings > Tap on your current phone number > Change Number). This seamlessly migrates your account to the new number without losing any data.