Move the wash-assist clips to the top of the window frame on both sides, if your vinyl window uses these assist clips. The wash-assist clips are small clips on each side of the window frame that disengage the top of the sash when you tilt the window out for cleaning.
Grasp the top of the upper sash, and push it into the window opening until you hear it click into place. If necessary, push the two latches on the top edge of the frame toward the center of the window when pushing the sash back into the frame Raise the upper sash to the top of the window frame until it stops.
Grab the top of the lower sash, and push it into the window frame until it clicks into position. The click you hear are the cleaning lock pins reengaging into the frame.
Lower the sash, and lock the two sashes together with the window lock. If the window does not lock, the lower sash is not fully engaged in the frame. Push the upper corners into the frame until you hear the latches click into position.