Panorama corrector

Photoshop CC has a tool called Perspective Crop that would do this, but it still not too hard with CS5. 

Use the Pen tool to create a workpath box that contains the tiles.  Get it close up front, and then hold down the Ctrl (Cmd) key to fine tune the corner handles.

Make a rectangular shape with no fill and a small stroke (two or three pixels) and give the stroke a different colour to the path.   With CS5 you don't have any control of the path colour.  Just one of the many ways that CC is better.  You need to to decide on the size of your rectangle which you will use to align the distorted layer.  Note I have copied the tiles layer.

Make a new layer above the copied tiles.

Select the paint brush and make it fully hard and 5 pixels.

Stroke the path.

Select the stroked path and copied tiles layers and group them

If you don't need all that background, I'd be inclined to delete what you don't need as it will make the transform process easier

Now either Free Transform the Group, or make the group a Smart Object and then FT it.  I'll go with the former to keep it simple.

Ctrl T to start the Free Transform, and hold down the Ctrl key while dragging the corner handles.  Remember we are trying to align the red and cyan rectangles.

OK that, and drag out some guides to see how well you have done. If it was me, I would _have_ to put a clipping path around the tiles and remove the background.

Could you please post an example of the problem that needs correcting?