Some suggestions, as above they might jump and they can jump very far, start searching if quick and not out too long they can still be alive depending when jumped.
May just be very well hidden, have a second more calm look.
What filter do you have, turn off and have a look inside, have read on here how some have gotten caught inside the filter and some have still been alive!
Otherwise be patient and wait or (personally) have little route around in the tank as dead fish will raise ammonia levels.
Lastly any ornaments with holes in etc they could get stuck in? My friends got inside a tree trunk ornament through a small gap she thought couldn't fit and they ended up breaking the stump to get the fish out (still alive and kicking!) she acted quick.
Fingers crossed they are just hidden for you.