How to treat collapsed lung.

Hey, I am 34 years male in Islamabad, Pakistan. In the year 2011, I had pneumonia which collapsed my left lung. The doctors diagnosed it as 'pleural effusion' for which they prescribed medicines. In September, 2013, I did X-Ray which showed that my left lung has resized and shifted to the right side reducing its size. Then, the doctors aspirated a huge fluid(puss) from it. I also got it checked from doctors in Dubai and they said 'It's been collapsed and left a scar '. Although, I have been taking medicines again but there's no sign of improvement or recovery. Can anyone advise me how to get it recover or it will be with same forever.