Oh no!
I doubt that someone stole them..they would have taken cage and all.
All you can do is keep looking and calling to them. Set their cage back up with food/water where they can see it and possibly return to it. Put posters up around your town. Alert your neighbors. Call vets and rescue places in your area in case someone finds then and turns them in.
Sometimes playing a tape of other keets sounds might help attract them.
Good luck laila..I hope you find them.
What is the weather like where you live?

Tis the season for sooo much of this going on. Lost my bird(s)..or found bird(s)
If taking them out to enjoy the sunshine and fresh air make sure the cage is VERY secure. Tape or zip tie things closed. Including the base of cage.
Make sure the cage is STABLE. And never leave unattended!!! Never leave them in the hot sun where there is no shade they can get in to....

Other do's n don't anyone??