I lost my I phone with that sim and when I got a new iPhone x. I tried logging into my icloud on the new one but for security reasons it needed the verification sent to my old number but I can't get access to that number as it was stolen. How to reco

You need to start account recovery.

https://support.apple.com/en-us/HT204921

However, you CANNOT do that without confirming the phone number on file. You need to figure it out in order to continue.

Keep your trusted phone numbers up to date

To use two-factor authentication, you need at least one trusted phone number on file where you can receive verification codes. You can update your trusted phone numbers when you follow these steps:

1. Go to your Apple ID account page.
2. Sign in with your Apple ID.
3. Go to the Security section and click Edit.

If you want to add a phone number, click Add a Trusted Phone Number and enter the phone number. Choose to verify the number with a text message or automated phone call, and click Continue. To remove a trusted phone number, click next to the phone number you want to remove.