Multiple ViewPorts

I had make a window that is splitted to 4 parts .one for the perspective view and other for top , left , bottom views .but i have a problem when window redrawen all windows are erased except the last one (Perpective) .How to solve that problem ?

I assume you do something like this for each viewport.

1: Call glViewport to set viewport.
2: Clear the viewport with glClear
3: Setup matrices and draw.

Common problem here is step 2. glClear will clear the entire window, erasing all previous viewports. What you need to do is either clear only once, which will clear all viewports at the same time, or restrict the clear area. Restricting the clear area is done with glScissor.