There is none. Beg to support that you lost your recovery key, and MAYBE they might help you.

You had to write code on paper and put somewhere (like wallet or favorite book).

Yesterday I had the same problem ^^ I forgot where's my recover code and made a ticket to support. Fortunately I decided to look in my old txt files - and yes, i found it :)
Now i have 7-days trade block - its bad, but its better then 1 month waiting from support

I am glad I came across this thread. Just wrote down my own recovery code.

Wait, why didn't you change the forgotten password?

you could use KeePass from now on to keep track of passwords.. if you have a problem remembering them...

So, is there any way that can avoid 7 days hold ban when switching from current to another phone?

Same thing happened to me. This mobile authenticator is a pos. I only activated it so I can sell my cards, I'm deleting it afterwards, and back to old mail auth.

i think i might found a way, but i'm not sure. i deactivated all authorized devices and i think if i act like i lost my account it should work, because i got access to my email which is linked to steam and like said i deauthorized all devices. but im scared, even if i dont have to :D

Don't use a throwaway/forgotten email for a site where you have money involved. Ever.
Use a password manager if you cannot remember not only a password, but a login name either.

Contact support and pray they are not fed up with everything, so they may take a pity on you and reset your mobile authenticator. You'll get a 7-day trade lock though.

i had a similar issue when i switch phone carriers i did disable the mobile guard from my old phone first tho but what i had forgotten to do was remove the old phone number from my steam account and the only way to do that is with a text message to the old phone...that i no longer had,personally i think the current set up steam is using for phones is stupid and a bit ridiculous but that said,,you can do what i did put in a steam ticket and ask for them to remove you old number so that you can set up mobile guard on your new phone they will likely ask you for some private info to prove you are the owner of the account like last few games you have bought and what the credit card number was that you used for it as well as some other things the more info you give the faster the process will be it took me about a week and a half.

"Do you feel secure yet?"
-Valve

Welcome to the Mobile Authenticator, Piece of Shit since 2015, bringing harm, inconvience, hate and discrimination to a Steam client near you (Yeah, I hate it. Please spam support that their pos is pos).