I need help.

[Nito]

I used textnow to use the authenticator without a phone and since I was on vacation for a month the phone number expired. In result I had to change it, but steam sends smses to my old phone number which expired. When I asked for help they sent me a complicated message which I cannot wrap my head around.

Hello,

Thank you for contacting Steam Support.

In order to assist you with this issue, we must verify your ownership of the software and associated Steam Account(s).

Please provide as much of the following as possible:

If you have associated a phone number with your Steam account, please provide it.

If you registered software purchased at a retail location, please handwrite your Support Ticket Number _ on the quick reference card or sticker above the CD Key (the number should not be written on a separate piece of paper or inserted with an image editor) and reply with a digital photo or scan of the CD Key in .jpg format. Please ensure that you submit a full-color image, rather than a photocopy.

If you have any difficulty locating the CD Key on the packaging, please see the following link:
URL: http://support.steampowered.com/kb_article.php?ref=7480-WUSF-3601

Example scans:
http://support.steampowered.com/images/faq/2347-QDFN-4366/cdkey1.jpg
http://support.steampowered.com/images/faq/2347-QDFN-4366/cdkey2.jpg

If you added funds to your account using a Steam Wallet Code, please handwrite your Support Ticket Number _______ on the card or receipt above the code (the number should not be written on a separate piece of paper or inserted with an image editor) and reply with a digital photo or scan of the code in .jpg format. Please ensure that you submit a full-color image, rather than a photocopy.

If you purchased software through Steam through PayPal, please provide the PayPal account holder billing information (name and address) and the PayPal Invoice ID. The Invoice ID will be 16-18 digits long and comprised of only numbers. It may be listed as the Order Description Number.

After verifying your proof of ownership we will gladly assist you with this issue.

[DirtyFishy]

You need to give them your phone number.
If you bought a game from a store you need to scan the key in jpg image.

[Nito]

does it have to be a specific cd key?

[✿ My ✿]

Since you no longer have access to the old (expired) phone number they want you to provide proof of ownership before they can assist you with removing that number so you can add a new one.
Here's the help faq:
https://support.steampowered.com/kb_article.php?ref=8625-WRAH-9030#sold
and the faq about how to prove that you own that account:
https://support.steampowered.com/kb_article.php?ref=2268-EAFZ-9762
Hope this helps

[DirtyFishy]

Originally posted by man bucket:

does it have to be a specific cd key?

No.

[✿ My ✿]

Originally posted by man bucket:

does it have to be a specific cd key?

It doesn't have to be a CD Key it can be payment method details that you've used to buy games for that account (ie: your Paypal account details or credit card details etc)