Hello @Henda2,
If a guest sends a reservation inquiry you should have the option to pre-approve or decline.
If a guest sends a reservation request you have the option to accept or decline. Yhere's no pre-approve option in this case.
Typing in all capitals makes responders feel like you're shouting at them.
If you pre-approve an inquiry then it's up to the guest to respond in 24 h ours to make a booking. There will not be any confirmed booking until they do.
If you accept a reservation request then, provided the guests payment is successful then there will be a confirmed booking.
Your question is a bit confusing because the heading says "no link to pre-approve" but you then say "when I go in the Airbnb site and click on the preapprove or decline". If you clecked on "Decline" then there will definitely not be any reservation.
So I'm not sure whether you've received a reservation inquiry or a reservation request or whether you've clicked "Decline".
Difference between a Reservation “Inquiry” or “Req... - Airbnb Community
If the above doesn't explain the situation you can contact Airbnb support.
Type "contact airbnb" in the "Search the community" box on these forum pages where you posted your question. Scroll down a little in the list of suggestions that appears and click on the "Contact Airbnb: A Community Help Guide[UPDATED]" one. That lists phone numbers and ways to contact them via Twitter or Facebook.
Steve.