Sounds like you are in Burst Mode.
The Operating Instruction Manual - Page 10, shows how to set the camera to set the Single Mode Lever.
See item 23.
If that does not work, see if you can find a Factory reset Procedure in the manual.
There are so many settings that you can easily set something that is causing a problem.
A Factory reset will restore the camera to how it was set up when you first bought the camera.
That can get you out of many problems that you may have inadvertently caused.
If the Factory reset does not fix the problem, call Panasonic Repair. They are probably familiar with the problem.
Recently I owned Panasonic Lumix g1 mirrorless camera and new to photographic world but now my camera is always in timer mode..
It won't change to single, brust shooting mode no matter how much I use drive mode..
So,I am asking any veteran how have knowledge about this problem a solution!!!