Putt Thunderbird back to the original layout

Available layout options will probably do what you want. If you describe what you don't about your current layout and what you would prefer, someone here can help. A screen image would help too.

In the meantime, you may want to explore the options under the "View" menu and the "Layout" sub-menu if you are not already familiar with them. You can access the "View" menu in the application menu or in the ≡ menu. If you are using Windows and the application menu is not visible, press the <alt> key to show it.

My Bad i found the problem and its back to normal. Thanks

For the future, I would suggest you phrase you questions like as if we have no idea what "normal" of "Used to be" looked like.

Generally folk assume what they see is what we all see. Nothing could be further from the truth. Thunderbird comes in many themes and has now four supported operating systems and soon to be five so you need to be very explicit what you talk about anything visual. What we see is usually not what you do. If for no other reason that those that have used Thunderbird long enough to think they can offer others support have invariably customized it to their preferences.

I would suggest the use of screen shots to illustrate any question about layout